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Dyson ZA, Ashton PM, Khanam F, Chunga Chirambo A, Shakya M, Meiring JE, Tonks S, Karkey A, Msefula C, Clemens JD, Dunstan SJ, Baker S, Dougan G, Pitzer VE, Basnyat B, Qadri F, Heyderman RS, Gordon MA, Pollard AJ, Holt KE. Pathogen diversity and antimicrobial resistance transmission of Salmonella enterica serovars Typhi and Paratyphi A in Bangladesh, Nepal, and Malawi: a genomic epidemiological study. THE LANCET. MICROBE 2024; 5:100841. [PMID: 38996496 PMCID: PMC11300424 DOI: 10.1016/s2666-5247(24)00047-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 02/09/2024] [Accepted: 02/14/2024] [Indexed: 07/14/2024]
Abstract
BACKGROUND Enteric fever is a serious public health concern. The causative agents, Salmonella enterica serovars Typhi and Paratyphi A, frequently have antimicrobial resistance (AMR), leading to limited treatment options and poorer clinical outcomes. We investigated the genomic epidemiology, resistance mechanisms, and transmission dynamics of these pathogens at three urban sites in Africa and Asia. METHODS S Typhi and S Paratyphi A bacteria isolated from blood cultures of febrile children and adults at study sites in Dhaka (Bangladesh), Kathmandu (Nepal), and Blantyre (Malawi) during STRATAA surveillance were sequenced. Isolates were charactered in terms of their serotypes, genotypes (according to GenoTyphi and Paratype), molecular determinants of AMR, and population structure. We used phylogenomic analyses incorporating globally representative genomic data from previously published surveillance studies and ancestral state reconstruction to differentiate locally circulating from imported pathogen AMR variants. Clusters of sequences without any single-nucleotide variants in their core genome were identified and used to explore spatiotemporal patterns and transmission dynamics. FINDINGS We sequenced 731 genomes from isolates obtained during surveillance across the three sites between Oct 1, 2016, and Aug 31, 2019 (24 months in Dhaka and Kathmandu and 34 months in Blantyre). S Paratyphi A was present in Dhaka and Kathmandu but not Blantyre. S Typhi genotype 4.3.1 (H58) was common in all sites, but with different dominant variants (4.3.1.1.EA1 in Blantyre, 4.3.1.1 in Dhaka, and 4.3.1.2 in Kathmandu). Multidrug resistance (ie, resistance to chloramphenicol, co-trimoxazole, and ampicillin) was common in Blantyre (138 [98%] of 141 cases) and Dhaka (143 [32%] of 452), but absent from Kathmandu. Quinolone-resistance mutations were common in Dhaka (451 [>99%] of 452) and Kathmandu (123 [89%] of 138), but not in Blantyre (three [2%] of 141). Azithromycin-resistance mutations in acrB were rare, appearing only in Dhaka (five [1%] of 452). Phylogenetic analyses showed that most cases derived from pre-existing, locally established pathogen variants; 702 (98%) of 713 drug-resistant infections resulted from local circulation of AMR variants, not imported variants or recent de novo emergence; and pathogen variants circulated across age groups. 479 (66%) of 731 cases clustered with others that were indistinguishable by point mutations; individual clusters included multiple age groups and persisted for up to 2·3 years, and AMR determinants were invariant within clusters. INTERPRETATION Enteric fever was associated with locally established pathogen variants that circulate across age groups. AMR infections resulted from local transmission of resistant strains. These results form a baseline against which to monitor the impacts of control measures. FUNDING Wellcome Trust, Bill & Melinda Gates Foundation, EU Horizon 2020, and UK National Institute for Health and Care Research.
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Affiliation(s)
- Zoe A Dyson
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK; Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, VIC, Australia; Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK.
| | - Philip M Ashton
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi; Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Farhana Khanam
- International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Angeziwa Chunga Chirambo
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi; Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Mila Shakya
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - James E Meiring
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi; Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, UK; Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Susan Tonks
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Abhilasha Karkey
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal; Centre for Tropical Medicine and Global Health, Medical Sciences Division, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | | | - John D Clemens
- International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh; International Vaccine Institute, Seoul, South Korea
| | - Sarah J Dunstan
- Department of Infectious Diseases, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - Stephen Baker
- Department of Medicine, Cambridge Institute of Therapeutic Immunology and Infectious Diseases, University of Cambridge, Cambridge, UK
| | - Gordon Dougan
- Department of Medicine, Cambridge Institute of Therapeutic Immunology and Infectious Diseases, University of Cambridge, Cambridge, UK
| | - Virginia E Pitzer
- Department of Epidemiology of Microbial Diseases and the Public Health Modeling Unit, Yale School of Public Health, Yale University, New Haven, CT, USA
| | - Buddha Basnyat
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal; Centre for Tropical Medicine and Global Health, Medical Sciences Division, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Firdausi Qadri
- International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Robert S Heyderman
- NIHR Global Health Research Unit on Mucosal Pathogens, Division of Infection and Immunity, University College London, London, UK
| | - Melita A Gordon
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi; Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool, UK; Kamuzu University of Health Sciences, Blantyre, Malawi; Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Kathryn E Holt
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK; Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, VIC, Australia
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Alugupalli KR. Characterization of Turbo, a TLR Ligand-based Adjuvant for Glycoconjugate Vaccines. Immunohorizons 2024; 8:527-537. [PMID: 39093309 DOI: 10.4049/immunohorizons.2400040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Accepted: 07/08/2024] [Indexed: 08/04/2024] Open
Abstract
Many bacterial polysaccharide vaccines, including the typhoid Vi polysaccharide (ViPS) and tetravalent meningococcal polysaccharide conjugate (MCV4) vaccines, do not incorporate adjuvants and are not highly immunogenic, particularly in infants. I found that endotoxin, a TLR4 ligand in ViPS, contributes to the immunogenicity of typhoid vaccines. Because endotoxin is pyrogenic, and its levels are highly variable in vaccines, I developed monophosphoryl lipid A, a nontoxic TLR4 ligand-based adjuvant named Turbo. Admixing Turbo with ViPS and MCV4 vaccines improved their immunogenicity across all ages and eliminated booster requirement. To understand the characteristics of this adjuvanticity, I compared Turbo with alum. Unlike alum, which polarizes the response toward the IgG1 isotype, Turbo promoted Ab class switching to all IgG isotypes with affinity maturation; the magnitude of this IgG response is durable and accompanied by the presence of long-lived plasma cells in the mouse bone marrow. In striking contrast with the pathways employed by alum, Turbo adjuvanticity is independent of NLPR3, pyroptotic cell death effector Gasdermin D, and canonical and noncanonical inflammasome activation mediated by Caspase-1 and Caspase-11, respectively. Turbo adjuvanticity is primarily dependent on the MyD88 axis and is lost in mice deficient in costimulatory molecules CD86 and CD40, indicating that Turbo adjuvanticity includes activation of these pathways. Because Turbo formulations containing either monophosphoryl lipid A or TLR2 ligands, Pam2CysSerLys4, and Pam3CysSerLys4 help generate Ab response of all IgG isotypes, as an adjuvant Turbo can improve the immunogenicity of glycoconjugate vaccines against a wide range of bacterial pathogens whose elimination requires appropriate IgG isotypes.
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Affiliation(s)
- Kishore R Alugupalli
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
- TurboVax Inc., Philadelphia, PA
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3
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Ruape WA, Mond C, Toroi W, Max B, Chanoan J, Duke T. Typhoid fever in children in Goroka, Papua New Guinea. J Paediatr Child Health 2024; 60:188-192. [PMID: 38661078 DOI: 10.1111/jpc.16553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/06/2024] [Accepted: 04/16/2024] [Indexed: 04/26/2024]
Abstract
BACKGROUND Typhoid is endemic in many low-income countries, including in Papua New Guinea. This study aimed to describe the burden and clinical features of typhoid in children in a provincial hospital, to describe environmental conditions that lead to typhoid, and to document the antibiotic sensitivity of Salmonella spp. in the Eastern Highlands Province. METHODS A combined retrospective and prospective study of children admitted to with clinical features of typhoid to the Goroka Hospital throughout 2022. RESULTS The study included 98 children, of which 54% were female. The median age was 8 (IQR 5-10.6) years. Over 60% of the patients were from Goroka District, the peri-urban area encompassing the town and surrounds. Ninety-four percent (92) of the patients used a pit latrine as a toilet and only 28% had access to treated water. Neuropsychiatric symptoms were common (60%), as was leukopenia (48%), thrombocytopenia (52%) and anaemia (42%). Thirty-seven patients had positive blood cultures for Salmonella typhi; all isolates were sensitive to third-generation cephalosporins, pefloxacin, ampicillin, trimethoprim and sulfamethoxazole, and only 54% sensitive to chloramphenicol. The median duration of hospitalisation was 6 days (IQR). There were no deaths. CONCLUSION Prompt public health actions are needed to reduce the burden of typhoid infection in the Papua New Guinea. The conjugate typhoid vaccine should be considered in the highlands region, where typhoid is most endemic.
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Affiliation(s)
| | - Casparia Mond
- Goroka Provincial Hospital, Goroka, Papua New Guinea
| | - Watson Toroi
- Goroka Provincial Hospital, Goroka, Papua New Guinea
| | - Becky Max
- Goroka Provincial Hospital, Goroka, Papua New Guinea
| | | | - Trevor Duke
- School of Medicine and Health Sciences, University of PNG, Port Moresby, Papua New Guinea
- Department of Paediatrics and Intensive Care Unit, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria, Australia
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Alugupalli KR. A TLR4 ligand-based adjuvant for promoting the immunogenicity of typhoid subunit vaccines. Front Immunol 2024; 15:1383476. [PMID: 38799439 PMCID: PMC11116679 DOI: 10.3389/fimmu.2024.1383476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/19/2024] [Indexed: 05/29/2024] Open
Abstract
None of the typhoid Vi Polysaccharide (ViPS) subunit vaccines incorporate adjuvants, and the immunogenicity of ViPS vaccines (e.g. Typbar TCV® and Typhim Vi®) is in part due to associated TLR4 ligands such as endotoxin present in these vaccines. Since endotoxin content in vaccines is variable and kept very low due to inherent toxicity, it was hypothesized that incorporating a defined amount of a non-toxic TLR4-ligand such as monophosphoryl lipid A in ViPS vaccines would improve their immunogenicity. To test this hypothesis, a monophosphoryl lipid A-based adjuvant formulation named Turbo was developed. Admixing Turbo with Typbar TCV® (ViPS-conjugated to tetanus toxoid) increased the levels of anti-ViPS IgM, IgG1, IgG2b, IgG2a/c, and IgG3 in inbred and outbred mice. In infant mice, a single immunization with Turbo adjuvanted Typbar TCV® resulted in a significantly increased and durable IgG response and improved the control of bacterial burden compared to mice immunized without Turbo. Similarly, when adjuvanted with Turbo, the antibody response and control of bacteremia were also improved in mice immunized with Typhim Vi®, an unconjugated vaccine. The immunogenicity of unconjugated ViPS is inefficient in young mice and is lost in adult mice when immunostimulatory ligands in ViPS are removed. Nevertheless, when adjuvanted with Turbo, poorly immunogenic ViPS induced a robust IgG response in young and adult mice, and this was observed even under antigen-limiting conditions. These data suggest that incorporation of Turbo as an adjuvant will make typhoid vaccines more immunogenic regardless of their intrinsic immunogenicity or conjugation status and maximize the efficacy across all ages.
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Affiliation(s)
- Kishore R. Alugupalli
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA, United States
- TurboVax Inc, Philadelphia, PA, United States
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Weyant C, Hooda Y, Munira SJ, Lo NC, Ryckman T, Tanmoy AM, Kanon N, Seidman JC, Garrett D, Saha SK, Goldhaber-Fiebert JD, Saha S, Andrews JR. Cost-effectiveness and public health impact of typhoid conjugate vaccine introduction strategies in Bangladesh. Vaccine 2024; 42:2867-2876. [PMID: 38531727 PMCID: PMC11033679 DOI: 10.1016/j.vaccine.2024.03.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 03/13/2024] [Accepted: 03/14/2024] [Indexed: 03/28/2024]
Abstract
PURPOSE Typhoid fever causes substantial morbidity and mortality in Bangladesh. The government of Bangladesh plans to introduce typhoid conjugate vaccines (TCV) in its expanded program on immunization (EPI) schedule. However, the optimal introduction strategy in addition to the costs and benefits of such a program are unclear. METHODS We extended an existing mathematical model of typhoid transmission to integrate cost data, clinical incidence data, and recently conducted serosurveys in urban, semi-urban, and rural areas. In our primary analysis, we evaluated the status quo (i.e., no vaccination) and eight vaccine introduction strategies including routine and 1-time campaign strategies, which differed by age groups targeted and geographic focus. Model outcomes included clinical incidence, seroincidence, deaths, costs, disability-adjusted life years (DALYs), and incremental cost-effectiveness ratios (ICERs) for each strategy. We adopted a societal perspective, 10-year model time horizon, and 3 % annual discount rate. We performed probabilistic, one-way, and scenario sensitivity analyses including adopting a healthcare perspective and alternate model time horizons. RESULTS We projected that all TCV strategies would be cost saving compared to the status quo. The preferred strategy was a nationwide introduction of TCV at 9-12 months of age with a single catch-up campaign for children ages 1-15, which was cost saving compared to all other strategies and the status quo. In the 10 years following implementation, we projected this strategy would avert 3.77 million cases (95 % CrI: 2.60 - 5.18), 11.31 thousand deaths (95 % CrI: 3.77 - 23.60), and save $172.35 million (95 % CrI: -14.29 - 460.59) compared to the status quo. Our findings were broadly robust to changes in parameter values and willingness-to-pay thresholds. CONCLUSIONS We projected that nationwide TCV introduction with a catch-up campaign would substantially reduce typhoid incidence and very likely be cost saving in Bangladesh.
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Affiliation(s)
- Christopher Weyant
- Department of Health Policy and Center for Health Policy, Stanford School of Medicine and Freeman Spogli Institute, Stanford University, Stanford, CA, United States.
| | - Yogesh Hooda
- Child Health Research Foundation, Dhaka, Bangladesh
| | | | - Nathan C Lo
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, Stanford, CA, United States
| | - Theresa Ryckman
- Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States
| | | | - Naito Kanon
- Child Health Research Foundation, Dhaka, Bangladesh
| | | | | | - Samir K Saha
- Child Health Research Foundation, Dhaka, Bangladesh; Department of Microbiology, Bangladesh Shishu Hospital and Institute, Dhaka, Bangladesh
| | - Jeremy D Goldhaber-Fiebert
- Department of Health Policy and Center for Health Policy, Stanford School of Medicine and Freeman Spogli Institute, Stanford University, Stanford, CA, United States
| | - Senjuti Saha
- Child Health Research Foundation, Dhaka, Bangladesh
| | - Jason R Andrews
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, Stanford, CA, United States
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Uzzell CB, Abraham D, Rigby J, Troman CM, Nair S, Elviss N, Kathiresan L, Srinivasan R, Balaji V, Zhou NA, Meschke JS, John J, Kang G, Feasey N, Mohan VR, Grassly NC. Environmental Surveillance for Salmonella Typhi and its Association With Typhoid Fever Incidence in India and Malawi. J Infect Dis 2024; 229:979-987. [PMID: 37775091 PMCID: PMC11011185 DOI: 10.1093/infdis/jiad427] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/15/2023] [Accepted: 09/28/2023] [Indexed: 10/01/2023] Open
Abstract
BACKGROUND Environmental surveillance (ES) for Salmonella Typhi potentially offers a low-cost tool to identify communities with a high burden of typhoid fever. METHODS We developed standardized protocols for typhoid ES, including sampling site selection, validation, characterization; grab or trap sample collection, concentration; and quantitative PCR targeting Salmonella genes (ttr, staG, and tviB) and a marker of human fecal contamination (HF183). ES was implemented over 12 months in a historically high typhoid fever incidence setting (Vellore, India) and a lower incidence setting (Blantyre, Malawi) during 2021-2022. RESULTS S. Typhi prevalence in ES samples was higher in Vellore compared with Blantyre; 39/520 (7.5%; 95% confidence interval [CI], 4.4%-12.4%) vs 11/533 (2.1%; 95% CI, 1.1%-4.0%) in grab and 79/517 (15.3%; 95% CI, 9.8%-23.0%) vs 23/594 (3.9%; 95% CI, 1.9%-7.9%) in trap samples. Detection was clustered by ES site and correlated with site catchment population in Vellore but not Blantyre. Incidence of culture-confirmed typhoid in local hospitals was low during the study and zero some months in Vellore despite S. Typhi detection in ES. CONCLUSIONS ES describes the prevalence and distribution of S. Typhi even in the absence of typhoid cases and could inform vaccine introduction. Expanded implementation and comparison with clinical and serological surveillance will further establish its public health utility.
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Affiliation(s)
- Christopher B Uzzell
- Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Dilip Abraham
- Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Jonathan Rigby
- Malawi-Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Catherine M Troman
- Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Satheesh Nair
- Gastrointestinal Bacteria Reference Unit, UK Health Security Agency, London, United Kingdom
| | - Nicola Elviss
- Science Group, UK Health Security Agency, London, United Kingdom
| | | | - Rajan Srinivasan
- Department of Community Health, Christian Medical College, Vellore, India
| | - Veeraraghavan Balaji
- Division of Antimicrobial Resistance and Surveillance, Christian Medical College, Vellore, India
| | - Nicolette A Zhou
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, Washington, USA
| | - John Scott Meschke
- Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, Washington, USA
| | - Jacob John
- Department of Community Health, Christian Medical College, Vellore, India
| | - Gagandeep Kang
- Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Nicholas Feasey
- Malawi-Liverpool Wellcome Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | | | - Nicholas C Grassly
- Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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7
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Batool R, Qamar ZH, Salam RA, Yousafzai MT, Ashorn P, Qamar FN. Efficacy of typhoid vaccines against culture-confirmed Salmonella Typhi in typhoid endemic countries: a systematic review and meta-analysis. Lancet Glob Health 2024; 12:e589-e598. [PMID: 38485426 DOI: 10.1016/s2214-109x(23)00606-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 03/19/2024]
Abstract
BACKGROUND Typhoid is a serious public health threat in many low-income and middle-income countries. Several vaccines for typhoid have been recommended by WHO for typhoid prevention in endemic countries. This study aimed to review the efficacy of typhoid vaccines against culture-confirmed Salmonella enterica serovar Typhi. METHODS We searched the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase for studies published in English between Jan 1, 1986 and Nov 2, 2023. We included randomised controlled trials (RCTs) comparing typhoid vaccines with a placebo or another vaccine. This meta-analysis evaluated the efficacy and safety of several typhoid vaccines, including live attenuated oral Ty21a vaccine, Vi capsular polysaccharide (Vi-PS), Vi polysaccharide conjugated to recombinant Pseudomonas aeruginosa exotoxin A vaccine (Vi-rEPA), and Vi-tetanus toxoid conjugate vaccine (TCV). The certainty of evidence for key outcomes was evaluated using Grading of Recommendations, Assessment, Development, and Evaluations methodology. The outcome of interest was typhoid fever confirmed by the isolation of Salmonella enterica serovar Typhi in blood and adverse events following immunisation. This study is registered with PROSPERO (CRD42021241043). FINDINGS We included 14 RCTs assessing four different vaccines (Ty21a: four trials; Vi-PS: five trials; Vi-rEPA: one trial; TCV: four trials) involving 585 253 participants. All trials were conducted in typhoid endemic countries and the age of participants ranged from 6 months to 50 years. The pooled efficacy against typhoid fever was 45% (95% CI 33-55%; four trials; 247 649 participants; I2 59%; moderate certainty) for Ty21a and 58% (44-69%; five trials; 214 456 participants; I2 34%; moderate certainty) for polysaccharide Vi-PS. The cumulative efficacy of two doses of Vi-rEPA vaccine at 2 years was 91% (88-96%; one trial; 12 008 participants; moderate certainty). The pooled efficacy of a single shot of TCV at 2 years post-immunisation was 83% (77-87%; four trials; 111 130 participants; I2 0%; moderate certainty). All vaccines were safe, with no serious adverse effects reported in the trials. INTERPRETATION The existing data from included trials provide promising results regarding the efficacy and safety of the four recommended typhoid vaccines. TCV and Vi-rEPA were found to have the highest efficacy at 2 years post-immunisation. However, follow-up data for Vi-rEPA are scarce and only TCV is pre-qualified by WHO. Therefore, roll-out of TCV into routine immunisation programmes in typhoid endemic settings is highly recommended. FUNDING There was no funding source for this study.
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Affiliation(s)
- Rabab Batool
- Department of Epidemiology and Biostatistics, Aga Khan University Hospital, Karachi, Pakistan; Department of Pediatrics and Child Health, Aga Khan University Hospital, Karachi, Pakistan; Centre for Child, Adolescent, and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Zoya Haq Qamar
- Liaquat National Hospital and Medical College, Karachi, Pakistan
| | | | - Mohammad Tahir Yousafzai
- Department of Pediatrics and Child Health, Aga Khan University Hospital, Karachi, Pakistan; The Kirby Institute, University of New South Wales, Sydney, NSW, Australia
| | - Per Ashorn
- Centre for Child, Adolescent, and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Farah Naz Qamar
- Department of Pediatrics and Child Health, Aga Khan University Hospital, Karachi, Pakistan.
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Marks F, Im J, Park SE, Pak GD, Jeon HJ, Wandji Nana LR, Phoba MF, Mbuyi-Kalonji L, Mogeni OD, Yeshitela B, Panzner U, Cruz Espinoza LM, Beyene T, Owusu-Ansah M, Twumasi-Ankrah S, Yeshambaw M, Alemu A, Adewusi OJ, Adekanmbi O, Higginson E, Adepoju A, Agbi S, Cakpo EG, Ogunleye VO, Tunda GN, Ikhimiukor OO, Mbuyamba J, Toy T, Agyapong FO, Osei I, Amuasi J, Razafindrabe TJL, Raminosoa TM, Nyirenda G, Randriamampionona N, Seo HW, Seo H, Siribie M, Carey ME, Owusu M, Meyer CG, Rakotozandrindrainy N, Sarpong N, Razafindrakalia M, Razafimanantsoa R, Ouedraogo M, Kim YJ, Lee J, Zellweger RM, Kang SSY, Park JY, Crump JA, Hardy L, Jacobs J, Garrett DO, Andrews JR, Poudyal N, Kim DR, Clemens JD, Baker SG, Kim JH, Dougan G, Sugimoto JD, Van Puyvelde S, Kehinde A, Popoola OA, Mogasale V, Breiman RF, MacWright WR, Aseffa A, Tadesse BT, Haselbeck A, Adu-Sarkodie Y, Teferi M, Bassiahi AS, Okeke IN, Lunguya-Metila O, Owusu-Dabo E, Rakotozandrindrainy R. Incidence of typhoid fever in Burkina Faso, Democratic Republic of the Congo, Ethiopia, Ghana, Madagascar, and Nigeria (the Severe Typhoid in Africa programme): a population-based study. Lancet Glob Health 2024; 12:e599-e610. [PMID: 38485427 PMCID: PMC10951957 DOI: 10.1016/s2214-109x(24)00007-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/06/2023] [Accepted: 01/03/2024] [Indexed: 03/19/2024]
Abstract
BACKGROUND Typhoid Fever remains a major cause of morbidity and mortality in low-income settings. The Severe Typhoid in Africa programme was designed to address regional gaps in typhoid burden data and identify populations eligible for interventions using novel typhoid conjugate vaccines. METHODS A hybrid design, hospital-based prospective surveillance with population-based health-care utilisation surveys, was implemented in six countries in sub-Saharan Africa. Patients presenting with fever (≥37·5°C axillary or ≥38·0°C tympanic) or reporting fever for three consecutive days within the previous 7 days were invited to participate. Typhoid fever was ascertained by culture of blood collected upon enrolment. Disease incidence at the population level was estimated using a Bayesian mixture model. FINDINGS 27 866 (33·8%) of 82 491 participants who met inclusion criteria were recruited. Blood cultures were performed for 27 544 (98·8%) of enrolled participants. Clinically significant organisms were detected in 2136 (7·7%) of these cultures, and 346 (16·2%) Salmonella enterica serovar Typhi were isolated. The overall adjusted incidence per 100 000 person-years of observation was highest in Kavuaya and Nkandu 1, Democratic Republic of the Congo (315, 95% credible interval 254-390). Overall, 46 (16·4%) of 280 tested isolates showed ciprofloxacin non-susceptibility. INTERPRETATION High disease incidence (ie, >100 per 100 000 person-years of observation) recorded in four countries, the prevalence of typhoid hospitalisations and complicated disease, and the threat of resistant typhoid strains strengthen the need for rapid dispatch and implementation of effective typhoid conjugate vaccines along with measures designed to improve clean water, sanitation, and hygiene practices. FUNDING The Bill & Melinda Gates Foundation.
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Affiliation(s)
- Florian Marks
- International Vaccine Institute, Seoul, South Korea; Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK; Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany; Madagascar Institute for Vaccine Research, University of Antananarivo, Antananarivo, Madagascar.
| | - Justin Im
- International Vaccine Institute, Seoul, South Korea
| | - Se Eun Park
- International Vaccine Institute, Seoul, South Korea; Yonsei University Graduate School of Public Health, Seoul, South Korea; Yonsei University Graduate School of Public Health, Seoul, South Korea
| | - Gi Deok Pak
- International Vaccine Institute, Seoul, South Korea
| | - Hyon Jin Jeon
- International Vaccine Institute, Seoul, South Korea; Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK; Madagascar Institute for Vaccine Research, University of Antananarivo, Antananarivo, Madagascar
| | | | - Marie-France Phoba
- Department of Microbiology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo; Department of Medical Biology, Microbiology Service, University Teaching Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Lisette Mbuyi-Kalonji
- Department of Microbiology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo; Department of Medical Biology, Microbiology Service, University Teaching Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | | | | | | | | | - Tigist Beyene
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Michael Owusu-Ansah
- School of Public Health, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Sampson Twumasi-Ankrah
- School of Public Health, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana; Department of Statistics and Actuarial Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | | | - Ashenafi Alemu
- Department of Medicine, University of Ibadan, Ibadan, Nigeria
| | | | - Olukemi Adekanmbi
- Department of Medicine, University of Ibadan, Ibadan, Nigeria; Department of Community Medicine, University College Hospital, Ibadan, Nigeria
| | - Ellen Higginson
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK
| | - Akinlolu Adepoju
- Department of Paediatrics, University of Ibadan, Ibadan, Nigeria; Department of Community Medicine, University College Hospital, Ibadan, Nigeria
| | - Sarah Agbi
- Department of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Enoch G Cakpo
- Institut Supérieur des Sciences de la Population, Ouagadougou, Burkina Faso
| | - Veronica O Ogunleye
- Department of Community Medicine, University College Hospital, Ibadan, Nigeria
| | - Gaëlle Nkoji Tunda
- Department of Microbiology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo; Faculty of Medicine, Congo Protestant University, Kinshasa, Democratic Republic of the Congo
| | - Odion O Ikhimiukor
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria
| | - Jules Mbuyamba
- Department of Microbiology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo; Department of Medical Biology, Microbiology Service, University Teaching Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Trevor Toy
- International Vaccine Institute, Seoul, South Korea
| | - Francis Opoku Agyapong
- Department of Clinical Microbiology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Isaac Osei
- Medical Research Council Unit, The Gambia at London School of Hygiene & Tropical Medicine, Banjul, The Gambia; Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - John Amuasi
- School of Public Health, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana; Bernhard Nocht Institute of Tropical Medicine, Hamburg, Germany; Kumasi Centre for Collaborative Research in Tropical Medicine (KCCR), Kumasi, Ghana
| | | | - Tiana Mirana Raminosoa
- Madagascar Institute for Vaccine Research, University of Antananarivo, Antananarivo, Madagascar
| | | | | | | | - Hyejin Seo
- International Vaccine Institute, Seoul, South Korea
| | | | - Megan E Carey
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK; International AIDS Vaccine Initiative, Chelsea & Westminster Hospital, London, UK
| | - Michael Owusu
- Department of Medical Diagnostics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana; Centre for Health System Strengthening (CfHSS), Kumasi, Ghana; Kumasi Centre for Collaborative Research in Tropical Medicine (KCCR), Kumasi, Ghana
| | - Christian G Meyer
- Institute of Tropical Medicine, Eberhard-Karls University Tübingen, Tübingen, Germany; Duy Tan University, Da Nang, Viet Nam
| | | | - Nimarko Sarpong
- School of Public Health, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | | | | | | | | | - Jooah Lee
- International Vaccine Institute, Seoul, South Korea; Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | | | | | - Ju Yeon Park
- International Vaccine Institute, Seoul, South Korea; Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK
| | - John A Crump
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | - Liselotte Hardy
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Jan Jacobs
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium; Department of Microbiology, Immunology and Transplantation, KU Leuven, Leuven Belgium
| | | | - Jason R Andrews
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | | | | | - John D Clemens
- International Vaccine Institute, Seoul, South Korea; Jonathan and Karin Fielding School of Public Health, University of California Los Angeles, Los Angeles, CA, USA
| | - Stephen G Baker
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK
| | - Jerome H Kim
- International Vaccine Institute, Seoul, South Korea; Department of Life Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea
| | - Gordon Dougan
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK
| | - Jonathan D Sugimoto
- International Vaccine Institute, Seoul, South Korea; Epidemiologic Research and Information Center, Cooperative Studies Program, Office of Research and Development, United States Department of Veterans Affairs, Seattle, WA, USA; Department of Epidemiology, University of Washington, Seattle, WA, USA; Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle WA USA
| | - Sandra Van Puyvelde
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK; Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, Antwerpen, Belgium
| | - Aderemi Kehinde
- Department of Medical Microbiology and Parasitology, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Oluwafemi A Popoola
- Department of Community Medicine, University College Hospital, Ibadan, Nigeria; Department of Community Medicine, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | | | - Robert F Breiman
- Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA; Infectious Diseases and Oncology Research Institute, University of the Witwatersrand, Johannesburg, South Africa
| | | | - Abraham Aseffa
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Birkneh Tilahun Tadesse
- International Vaccine Institute, Seoul, South Korea; Division of Clinical Pharmacology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden; Center for Innovative Drug Development and Therapeutic Trials for Africa, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | | | - Yaw Adu-Sarkodie
- School of Public Health, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana; Department of Clinical Microbiology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | | | | | - Iruka N Okeke
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria
| | - Octavie Lunguya-Metila
- Department of Microbiology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo; Department of Medical Biology, Microbiology Service, University Teaching Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Ellis Owusu-Dabo
- School of Public Health, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
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9
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Alugupalli KR. Monophosphoryl Lipid A-based Adjuvant to Promote the Immunogenicity of Multivalent Meningococcal Polysaccharide Conjugate Vaccines. Immunohorizons 2024; 8:317-325. [PMID: 38625118 PMCID: PMC11066721 DOI: 10.4049/immunohorizons.2400013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 04/01/2024] [Indexed: 04/17/2024] Open
Abstract
Activation of the adaptive immune system requires the engagement of costimulatory pathways in addition to B and T cell Ag receptor signaling, and adjuvants play a central role in this process. Many Gram-negative bacterial polysaccharide vaccines, including the tetravalent meningococcal conjugate vaccines (MCV4) and typhoid Vi polysaccharide vaccines, do not incorporate adjuvants. The immunogenicity of typhoid vaccines is due to the presence of associated TLR4 ligands in these vaccines. Because the immunogenicity of MCV4 is poor and requires boosters, I hypothesized that TLR4 ligands are absent in MCV4 and that incorporation of a TLR4 ligand-based adjuvant would improve their immunogenicity. Consistent with this hypothesis, two Food and Drug Administration-approved MCV4 vaccines, MENVEO and MenQuadfi, lack TLR4 ligands. Admixing monophosphoryl lipid A, a TLR4 ligand-based adjuvant formulation named "Turbo" with MCV4 induced significantly improved IgM and IgG responses to all four meningococcal serogroup polysaccharides in adult and aged mice after a single immunization. Furthermore, in infant mice, a single booster was sufficient to promote a robust IgG response and 100% seroconversion when MCV4 was adjuvanted with Turbo. Turbo upregulated the expression of the costimulatory molecules CD40 and CD86 on B cells, and Turbo-driven adjuvanticity is lost in mice deficient in CD40 and CD86. These data suggest that Turbo induces the required costimulatory molecules for its adjuvant activity and that incorporation of Turbo could make bacterial polysaccharide vaccines more immunogenic, minimize booster requirements, and be cost-effective, particularly for those individuals in low- and middle-income and disease-endemic countries.
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Affiliation(s)
- Kishore R. Alugupalli
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA; and TurboVax Inc., Philadelphia, PA
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10
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Sukri L, Banza A, Shafer K, Sanoussi Y, Neuzil KM, Sani R. Typhoid intestinal perforation in Francophone Africa, a scoping review. PLOS GLOBAL PUBLIC HEALTH 2024; 4:e0003056. [PMID: 38551919 PMCID: PMC10980251 DOI: 10.1371/journal.pgph.0003056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 03/04/2024] [Indexed: 04/01/2024]
Abstract
Typhoid intestinal perforation (TIP) is a leading cause of peritonitis and indication for emergency surgery in Africa, with reported mortality rates up to 30% in pediatric patients. Currently, data on TIP in Western databases are primarily from countries that speak English, likely due to non-English publication and citation biases. Despite the high burden of infectious diseases in Francophone Africa, data from these countries regarding TIP remain limited. This study aims to highlight the incidence and morbidity of TIP in Francophone African countries using an extended search algorithm. We conducted a scoping review using the PubMed, EMBASE, and SCOPUS databases with the keywords "peritonitis", "non-traumatic ileal perforation", and "typhoid" in Francophone African countries. Additionally, we contacted surgeons in Africa and concurrently used citation chasing to obtain data not found in western databases. In total, 32 studies from 12 countries were identified and included in this review. A total of 22 publications were in French. Patient median age was 20 years and TIP caused a median of 35% of acute peritonitis cases. Mortality rates ranged from 6-37% (median: 16%). Rate of complications ranged from 15-92% (median: 46%). Ileostomy creation as a treatment for TIP varied between hospitals (0-79%), with the highest rates reported in Niger. In Francophone Africa, TIP is associated with high morbidity and mortality, most commonly in children and young adults. Interventions, including improved sanitation and the introduction of typhoid conjugate vaccines into routine vaccination programs, have the potential to significantly decrease typhoid fever and its complications.
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Affiliation(s)
- Leah Sukri
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Audry Banza
- Département de Chirurgie, Hôpital de la SIM, Galmi, Niger
| | | | | | - Kathleen M. Neuzil
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Rachid Sani
- Département de Chirurgie et Spécialités Chirurgicales, Hôpital National de Niamey, Niamey, Niger
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11
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Bijukchhe SM, Gurung M, Pokhrel B, Shakya M, Pant D, Maskey P, Maskey H, Dhakal B, Rajkarkinar S, Bista S, Voysey M, Mujadidi YF, Kim YC, Atherton R, Jones E, Mclean F, Shrestha S, Hill M, Nyland KT, Kelly S, O'reilly P, Sah GP, Basnyat B, Pollard AJ, Shrestha S. Immune responses to typhoid conjugate vaccine in a two dose schedule among Nepalese children <2 years of age. Vaccine 2024; 42:2018-2025. [PMID: 38395723 DOI: 10.1016/j.vaccine.2024.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 01/29/2024] [Accepted: 02/02/2024] [Indexed: 02/25/2024]
Abstract
BACKGROUND Previously, the Vi-typhoid conjugate vaccine (Vi-TT) was found to be highly efficacious in Nepalese children under 16 years of age. We assessed the immunogenicity of Vi-TT at 9 and 12 months of age and response to a booster dose at 15 months of age. METHODS Infants were recruited at Patan Hospital, Kathmandu and received an initial dose of Vi-TT at 9 or 12 months of age with a booster dose at 15 months of age. Blood was taken at four timepoints, and antibody titres were measured using a commercial ELISA kit. The primary study outcome was seroconversion (4-fold rise in antibody titre) of IgG one month after both the doses. FINDINGS Fifty children were recruited to each study group.Some visits were disrupted by the COVID19 pandemic and occurred out of protocol windows.Both the study groups attained 100 % IgG seroconversion after the initial dose. IgG seroconversion in the 9-month group was significantly higher than in the 12-month group (68.42 % vs 25.8 %, p < 0.001). Among individuals who attended visits per protocol, IgG seroconversion after the first dose occurred in 100 % of individuals (n = 27/27 in 9-month and n = 32/32 in 12-month group). However, seroconversion rates after the second dose were 80 % in the 9-month and 0 % in the shorter dose-interval 12-month group (p < 0.001) (n = 16/20 and n = 0/8, respectively). INTERPRETATION Vi-TT is highly immunogenic at both 9 and 12 months of age. Stronger response to a booster in the 9-month group is likely due to the longer interval between doses.
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Affiliation(s)
- Sanjeev M Bijukchhe
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal; Department of Paediatrics, University of Oxford, Oxford, United Kingdom.
| | - Meeru Gurung
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Bhishma Pokhrel
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Mila Shakya
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Dikshya Pant
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Pratistha Maskey
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Himang Maskey
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Babita Dhakal
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Shristy Rajkarkinar
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Sabitri Bista
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Merryn Voysey
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Yama F Mujadidi
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Young Chan Kim
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Rachel Atherton
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Elizabeth Jones
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Florence Mclean
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Sonu Shrestha
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Matilda Hill
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | | | - Sarah Kelly
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Peter O'reilly
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Ganesh Prasad Sah
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Buddha Basnyat
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Andrew J Pollard
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Shrijana Shrestha
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
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12
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Gordon MA. Tackling non-typhoidal Salmonella with humility. Nat Microbiol 2024; 9:582-583. [PMID: 38413835 DOI: 10.1038/s41564-024-01623-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Affiliation(s)
- Melita A Gordon
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi.
- Department of Clinical Infection, Microbiology and Infection, Institute of Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK.
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13
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Agarwal N, Gupta N, Nishant, H S S, Dutta T, Mahajan M. Typhoid Conjugate Vaccine: A Boon for Endemic Regions. Cureus 2024; 16:e56454. [PMID: 38650789 PMCID: PMC11034893 DOI: 10.7759/cureus.56454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2024] [Indexed: 04/25/2024] Open
Abstract
Typhoid fever has the highest disease burden in countries in low- and middle-income countries, primarily located in Asia and Sub-Saharan Africa. Previous typhoid vaccines such as the live attenuated typhoid (Ty21a) vaccine and Vi (virulence) capsular polysaccharide vaccine had the limitation that they could not be administered with other standard childhood immunizations and were ineffective in children under two years of age. To address these shortcomings of the previous vaccines, typhoid conjugate vaccines (TCVs) were developed and prequalified by the World Health Organization. Cross-reacting material and tetanus toxoid are widely used as carrier proteins in TCVs. According to various studies, TCV has higher efficacy, has a more extended protection period, and is safe and immunogenic in infants as young as six months. This review article aims to comprehensively appraise the data available on TCVs' efficacy, duration of protection, safety, and immunogenicity in endemic regions.
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Affiliation(s)
- Nitesh Agarwal
- Department of Pediatrics, Southern Gem Hospital, Hyderabad, IND
| | - Naveen Gupta
- Department of Pediatrics, Happy Family Hospital, Karnal, IND
| | - Nishant
- Department of Pediatrics, Nihan Medical Children Hospital, Patna, IND
| | - Surendra H S
- Department of Pediatrics, Natus Women and Children Hospital, Bengaluru, IND
| | - Trayambak Dutta
- Department of Infectious Disease, Zydus Lifesciences, Ahmedabad, IND
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14
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Ashton PM, Chunga Chirambo A, Meiring JE, Patel PD, Mbewe M, Silungwe N, Chizani K, Banda H, Heyderman RS, Dyson ZA, MacPherson P, Henrion MYR, Holt KE, Gordon MA. Evaluating the relationship between ciprofloxacin prescription and non-susceptibility in Salmonella Typhi in Blantyre, Malawi: an observational study. THE LANCET. MICROBE 2024; 5:e226-e234. [PMID: 38387472 PMCID: PMC10914669 DOI: 10.1016/s2666-5247(23)00327-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 10/02/2023] [Accepted: 10/06/2023] [Indexed: 02/24/2024]
Abstract
BACKGROUND Ciprofloxacin is the first-line drug for treating typhoid fever in many countries in Africa with a high disease burden, but the emergence of non-susceptibility poses a challenge to public health programmes. Through enhanced surveillance as part of vaccine evaluation, we investigated the occurrence and potential determinants of ciprofloxacin non-susceptibility in Blantyre, Malawi. METHODS We conducted systematic surveillance of typhoid fever cases and antibiotic prescription in two health centres in Blantyre, Malawi, between Oct 1, 2016, and Oct 31, 2019, as part of the STRATAA and TyVAC studies. In addition, blood cultures were taken from eligible patients presenting at Queen Elizabeth Central Hospital, Blantyre, as part of routine diagnosis. Inclusion criteria were measured or reported fever, or clinical suspicion of sepsis. Microbiologically, we identified Salmonella enterica serotype Typhi (S Typhi) isolates with a ciprofloxacin non-susceptible phenotype from blood cultures, and used whole-genome sequencing to identify drug-resistance mutations and phylogenetic relationships. We constructed generalised linear regression models to investigate associations between the number of ciprofloxacin prescriptions given per month to study participants and the proportion of S Typhi isolates with quinolone resistance-determining region (QRDR) mutations in the following month. FINDINGS From 46 989 blood cultures from Queen Elizabeth Central Hospital, 502 S Typhi isolates were obtained, 30 (6%) of which had either decreased ciprofloxacin susceptibility, or ciprofloxacin resistance. From 11 295 blood cultures from STRATAA and TyVAC studies, 241 microbiologically confirmed cases of typhoid fever were identified, and 198 isolates from 195 participants sequenced (mean age 12·8 years [SD 10·2], 53% female, 47% male). Between Oct 1, 2016, and Aug 31, 2019, of 177 typhoid fever cases confirmed by whole-genome sequencing, four (2%) were caused by S Typhi with QRDR mutations, compared with six (33%) of 18 cases between Sept 1 and Oct 31, 2019. This increase was associated with a preceding spike in ciprofloxacin prescriptions. Every additional prescription of ciprofloxacin given to study participants in the preceding month was associated with a 4·2% increase (95% CI 1·8-7·0) in the relative risk of isolating S Typhi with a QRDR mutation (p=0·0008). Phylogenetic analysis showed that S Typhi isolates with QRDR mutations from September and October, 2019, belonged to two distinct subclades encoding two different QRDR mutations, and were closely related (4-10 single-nucleotide polymorphisms) to susceptible S Typhi endemic to Blantyre. INTERPRETATION We postulate a causal relationship between increased ciprofloxacin prescriptions and an increase in fluoroquinolone non-susceptibility in S Typhi. Decreasing ciprofloxacin use by improving typhoid diagnostics, and reducing typhoid fever cases through the use of an efficacious vaccine, could help to limit the emergence of resistance. FUNDING Wellcome Trust, Bill & Melinda Gates Foundation, and National Institute for Health and Care Research (UK).
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Affiliation(s)
- Philip M Ashton
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi; Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool, UK.
| | - Angeziwa Chunga Chirambo
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi; Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool, UK; Department of Medical Laboratory Sciences, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - James E Meiring
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi; Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | | | - Maurice Mbewe
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi
| | - Niza Silungwe
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi
| | | | - Happy Banda
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi
| | - Robert S Heyderman
- Research Department of Infection, Division of Infection and Immunity, University College London, London, UK
| | - Zoe A Dyson
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK; Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, VIC, Australia; Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK
| | - Peter MacPherson
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi; Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK; School of Health & Wellbeing, University of Glasgow, Glasgow, UK
| | - Marc Y R Henrion
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi; Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Kathryn E Holt
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK; Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Melita A Gordon
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi; Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool, UK
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15
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Browne AJ, Chipeta MG, Fell FJ, Haines-Woodhouse G, Kashef Hamadani BH, Kumaran EAP, Robles Aguilar G, McManigal B, Andrews JR, Ashley EA, Audi A, Baker S, Banda HC, Basnyat B, Bigogo G, Ngoun C, Chansamouth V, Chunga A, Clemens JD, Davong V, Dougan G, Dunachie SJ, Feasey NA, Garrett DO, Gordon MA, Hasan R, Haselbeck AH, Henry NJ, Heyderman RS, Holm M, Jeon HJ, Karkey A, Khanam F, Luby SP, Malik FR, Marks F, Mayxay M, Meiring JE, Moore CE, Munywoki PK, Musicha P, Newton PN, Pak G, Phommasone K, Pokharel S, Pollard AJ, Qadri F, Qamar FN, Rattanavong S, Reiner B, Roberts T, Saha S, Saha S, Shakoor S, Shakya M, Simpson AJ, Stanaway J, Turner C, Turner P, Verani JR, Vongsouvath M, Day NPJ, Naghavi M, Hay SI, Sartorius B, Dolecek C. Estimating the subnational prevalence of antimicrobial resistant Salmonella enterica serovars Typhi and Paratyphi A infections in 75 endemic countries, 1990-2019: a modelling study. Lancet Glob Health 2024; 12:e406-e418. [PMID: 38365414 PMCID: PMC10882211 DOI: 10.1016/s2214-109x(23)00585-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 11/19/2023] [Accepted: 12/04/2023] [Indexed: 02/18/2024]
Abstract
BACKGROUND Enteric fever, a systemic infection caused by Salmonella enterica serovars Typhi and Paratyphi A, remains a major cause of morbidity and mortality in low-income and middle-income countries. Enteric fever is preventable through the provision of clean water and adequate sanitation and can be successfully treated with antibiotics. However, high levels of antimicrobial resistance (AMR) compromise the effectiveness of treatment. We provide estimates of the prevalence of AMR S Typhi and S Paratyphi A in 75 endemic countries, including 30 locations without data. METHODS We used a Bayesian spatiotemporal modelling framework to estimate the percentage of multidrug resistance (MDR), fluoroquinolone non-susceptibility (FQNS), and third-generation cephalosporin resistance in S Typhi and S Paratyphi A infections for 1403 administrative level one districts in 75 endemic countries from 1990 to 2019. We incorporated data from a comprehensive systematic review, public health surveillance networks, and large multicountry studies on enteric fever. Estimates of the prevalence of AMR and the number of AMR infections (based on enteric fever incidence estimates by the Global Burden of Diseases study) were produced at the country, super-region, and total endemic area level for each year of the study. FINDINGS We collated data from 601 sources, comprising 184 225 isolates of S Typhi and S Paratyphi A, covering 45 countries over 30 years. We identified a decline of MDR S Typhi in south Asia and southeast Asia, whereas in sub-Saharan Africa, the overall prevalence increased from 6·0% (95% uncertainty interval 4·3-8·0) in 1990 to 72·7% (67·7-77·3) in 2019. Starting from low levels in 1990, the prevalence of FQNS S Typhi increased rapidly, reaching 95·2% (91·4-97·7) in south Asia in 2019. This corresponded to 2·5 million (1·5-3·8) MDR S Typhi infections and 7·4 million (4·7-11·3) FQNS S Typhi infections in endemic countries in 2019. The prevalence of third-generation cephalosporin-resistant S Typhi remained low across the whole endemic area over the study period, except for Pakistan where prevalence of third-generation cephalosporin resistance in S Typhi reached 61·0% (58·0-63·8) in 2019. For S Paratyphi A, we estimated low prevalence of MDR and third-generation cephalosporin resistance in all endemic countries, but a drastic increase of FQNS, which reached 95·0% (93·7-96·1; 3·5 million [2·2-5·6] infections) in 2019. INTERPRETATION This study provides a comprehensive and detailed analysis of the prevalence of MDR, FQNS, and third-generation cephalosporin resistance in S Typhi and S Paratyphi A infections in endemic countries, spanning the last 30 years. Our analysis highlights the increasing levels of AMR in this preventable infection and serves as a resource to guide urgently needed public health interventions, such as improvements in water, sanitation, and hygiene and typhoid fever vaccination campaigns. FUNDING Fleming Fund, UK Department of Health and Social Care; Wellcome Trust; and Bill and Melinda Gates Foundation.
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16
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Patel PD, Liang Y, Meiring JE, Chasweka N, Patel P, Misiri T, Mwakiseghile F, Wachepa R, Banda HC, Shumba F, Kawalazira G, Dube Q, Nampota-Nkomba N, Nyirenda OM, Girmay T, Datta S, Jamka LP, Tracy JK, Laurens MB, Heyderman RS, Neuzil KM, Gordon MA. Efficacy of typhoid conjugate vaccine: final analysis of a 4-year, phase 3, randomised controlled trial in Malawian children. Lancet 2024; 403:459-468. [PMID: 38281499 PMCID: PMC10850983 DOI: 10.1016/s0140-6736(23)02031-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 07/18/2023] [Accepted: 09/18/2023] [Indexed: 01/30/2024]
Abstract
BACKGROUND Randomised controlled trials of typhoid conjugate vaccines among children in Africa and Asia have shown high short-term efficacy. Data on the durability of protection beyond 2 years are sparse. We present the final analysis of a randomised controlled trial in Malawi, encompassing more than 4 years of follow-up, with the aim of investigating vaccine efficacy over time and by age group. METHODS In this phase 3, double-blind, randomised controlled efficacy trial in Blantyre, Malawi, healthy children aged 9 months to 12 years were randomly assigned (1:1) by an unmasked statistician to receive a single dose of Vi polysaccharide conjugated to tetanus toxoid vaccine (Vi-TT) or meningococcal capsular group A conjugate (MenA) vaccine. Children had to have no previous history of typhoid vaccination and reside in the study areas for inclusion and were recruited from government schools and health centres. Participants, their parents or guardians, and the study team were masked to vaccine allocation. Nurses administering vaccines were unmasked. We did surveillance for febrile illness from vaccination until follow-up completion. The primary outcome was first occurrence of blood culture-confirmed typhoid fever. Eligible children who were randomly assigned and vaccinated were included in the intention-to-treat analyses. This trial is registered at ClinicalTrials.gov, NCT03299426. FINDINGS Between Feb 21, 2018, and Sept 27, 2018, 28 130 children were vaccinated; 14 069 were assigned to receive Vi-TT and 14 061 to receive MenA. After a median follow-up of 4·3 years (IQR 4·2-4·5), 24 (39·7 cases per 100 000 person-years) children in the Vi-TT group and 110 (182·7 cases per 100 000 person-years) children in the MenA group were diagnosed with a first episode of blood culture-confirmed typhoid fever. In the intention-to-treat population, efficacy of Vi-TT was 78·3% (95% CI 66·3-86·1), and 163 (129-222) children needed to be vaccinated to prevent one case. Efficacies by age group were 70·6% (6·4-93·0) for children aged 9 months to 2 years; 79·6% (45·8-93·9) for children aged 2-4 years; and 79·3% (63·5-89·0) for children aged 5-12 years. INTERPRETATION A single dose of Vi-TT is durably efficacious for at least 4 years among children aged 9 months to 12 years and shows efficacy in all age groups, including children younger than 2 years. These results support current WHO recommendations in typhoid-endemic areas for mass campaigns among children aged 9 months to 15 years, followed by routine introduction in the first 2 years of life. FUNDING Bill & Melinda Gates Foundation.
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Affiliation(s)
- Priyanka D Patel
- Malawi-Liverpool-Wellcome Program, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Yuanyuan Liang
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - James E Meiring
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Nedson Chasweka
- Malawi-Liverpool-Wellcome Program, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Pratiksha Patel
- Malawi-Liverpool-Wellcome Program, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Theresa Misiri
- Malawi-Liverpool-Wellcome Program, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Felistas Mwakiseghile
- Malawi-Liverpool-Wellcome Program, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Richard Wachepa
- Malawi-Liverpool-Wellcome Program, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Happy C Banda
- Malawi-Liverpool-Wellcome Program, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Florence Shumba
- Malawi-Liverpool-Wellcome Program, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Gift Kawalazira
- District Health Office, Blantyre District Council, Blantyre, Malawi
| | | | | | - Osward M Nyirenda
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Tsion Girmay
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Shrimati Datta
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Leslie P Jamka
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - J Kathleen Tracy
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Matthew B Laurens
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Robert S Heyderman
- Division of Infection and Immunity, University College London, London, UK
| | - Kathleen M Neuzil
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Melita A Gordon
- Malawi-Liverpool-Wellcome Program, Kamuzu University of Health Sciences, Blantyre, Malawi
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Tadesse BT, Cardona RSB, Marks F. Long-term protection conferred by typhoid conjugate vaccines: a step towards typhoid elimination? Lancet 2024; 403:413-415. [PMID: 38281498 DOI: 10.1016/s0140-6736(23)02350-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 10/17/2023] [Indexed: 01/30/2024]
Affiliation(s)
- Birkneh Tilahun Tadesse
- International Vaccine Institute, SNU Research Park, Seoul 08826, South Korea; Department of Gobal Public Health, Karolinska Institutet, Stockholm, Sweden; Center for Innovative Drug Development and Therapeutic Trials for Africa, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia.
| | | | - Florian Marks
- International Vaccine Institute, SNU Research Park, Seoul 08826, South Korea; Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK; Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany; Madagascar Institute for Vaccine Research, University of Antananarivo, Antananarivo, Madagascar
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18
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Jamrozik E, Littler K, Meln I, Van Molle W, Morel S, Olesen OF, Rubbrecht M, Balasingam S, Neels P. Ethical approval for controlled human infectious model clinical trial protocols - A workshop report. Biologicals 2024; 85:101748. [PMID: 38350349 PMCID: PMC11004724 DOI: 10.1016/j.biologicals.2024.101748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/28/2024] [Indexed: 02/15/2024] Open
Abstract
Controlled Human Infectious Model studies (CHIM) involve deliberately exposing volunteers to pathogens. To discuss ethical issues related to CHIM, the European Vaccine Initiative and the International Alliance for Biological Standardization organised the workshop "Ethical Approval for CHIM Clinical Trial Protocols", which took place on May 30-31, 2023, in Brussels, Belgium. The event allowed CHIM researchers, regulators, ethics committee (EC) members, and ethicists to examine the ethical criteria for CHIM and the role(s) of CHIM in pharmaceutical development. The discussions led to several recommendations, including continued assurance that routine ethical requirements are met, assurance that participants are well-informed, and that preparation of study documents must be both ethically and scientifically sound from an early stage. Study applications must clearly state the rationale for the challenge compared to alternative study designs. ECs need to have clear guidance and procedures for evaluating social value and assessing third-party risks. Among other things, public trust in research requires minimisation of harm to healthy volunteers and third-party risk. Other important considerations include appropriate stakeholder engagement, public education, and access to health care for participants after the study.
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Affiliation(s)
- Euzebiusz Jamrozik
- The Ethox Centre & Wellcome Centre for Ethics and Humanities, University of Oxford, Oxford, United Kingdom
| | - Katherine Littler
- Health Ethics and Governance Unit, Research for Health Department, Science Division, World Health Organization, Geneva, Switzerland
| | - Irina Meln
- European Vaccine Initiative, Heidelberg, Germany
| | | | | | - Ole F Olesen
- European Vaccine Initiative, Heidelberg, Germany
| | | | | | - Pieter Neels
- International Alliance for Biological Standardization (IABS), Lyon, France.
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Hooda Y, Islam S, Kabiraj R, Rahman H, Sarkar H, da Silva KE, Raju RS, Luby SP, Andrews JR, Saha SK, Saha S. Old tools, new applications: Use of environmental bacteriophages for typhoid surveillance and evaluating vaccine impact. PLoS Negl Trop Dis 2024; 18:e0011822. [PMID: 38358956 PMCID: PMC10868810 DOI: 10.1371/journal.pntd.0011822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 11/27/2023] [Indexed: 02/17/2024] Open
Abstract
Typhoid-conjugate vaccines (TCVs) provide an opportunity to reduce the burden of typhoid fever, caused by Salmonella Typhi, in endemic areas. As policymakers design vaccination strategies, accurate and high-resolution data on disease burden is crucial. However, traditional blood culture-based surveillance is resource-extensive, prohibiting its large-scale and sustainable implementation. Salmonella Typhi is a water-borne pathogen, and here, we tested the potential of Typhi-specific bacteriophage surveillance in surface water bodies as a low-cost tool to identify where Salmonella Typhi circulates in the environment. In 2021, water samples were collected and tested for the presence of Salmonella Typhi bacteriophages at two sites in Bangladesh: urban capital city, Dhaka, and a rural district, Mirzapur. Salmonella Typhi-specific bacteriophages were detected in 66 of 211 (31%) environmental samples in Dhaka, in comparison to 3 of 92 (3%) environmental samples from Mirzapur. In the same year, 4,620 blood cultures at the two largest pediatric hospitals of Dhaka yielded 215 (5%) culture-confirmed typhoid cases, and 3,788 blood cultures in the largest hospital of Mirzapur yielded 2 (0.05%) cases. 75% (52/69) of positive phage samples were collected from sewage. All isolated phages were tested against a panel of isolates from different Salmonella Typhi genotypes circulating in Bangladesh and were found to exhibit a diverse killing spectrum, indicating that diverse bacteriophages were isolated. These results suggest an association between the presence of Typhi-specific phages in the environment and the burden of typhoid fever, and the potential of utilizing environmental phage surveillance as a low-cost tool to assist policy decisions on typhoid control.
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Affiliation(s)
- Yogesh Hooda
- Child Health Research Foundation, Dhaka, Bangladesh
| | | | | | | | | | - Kesia E. da Silva
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | | | - Stephen P. Luby
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Jason R. Andrews
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Samir K. Saha
- Child Health Research Foundation, Dhaka, Bangladesh
- Department of Microbiology, Bangladesh Shishu Hospital and Institute, Dhaka, Bangladesh
| | - Senjuti Saha
- Child Health Research Foundation, Dhaka, Bangladesh
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20
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Smith C, Smith E, Rydlova A, Varro R, Hinton JCD, Gordon MA, Choy RKM, Liu X, Pollard AJ, Chiu C, Cooke GS, Gibani MM. Protocol for the challenge non-typhoidal Salmonella (CHANTS) study: a first-in-human, in-patient, double-blind, randomised, safety and dose-escalation controlled human infection model in the UK. BMJ Open 2024; 14:e076477. [PMID: 38199617 PMCID: PMC10806722 DOI: 10.1136/bmjopen-2023-076477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
INTRODUCTION Invasive non-typhoidal Salmonella (iNTS) serovars are a major cause of community-acquired bloodstream infections in sub-Saharan Africa (SSA). In this setting, Salmonella enterica serovar Typhimurium accounts for two-thirds of infections and is associated with an estimated case fatality rate of 15%-20%. Several iNTS vaccine candidates are in early-stage assessment which-if found effective-would provide a valuable public health tool to reduce iNTS disease burden. The CHANTS study aims to develop a first-in-human Salmonella Typhimurium controlled human infection model, which can act as a platform for future vaccine evaluation, in addition to providing novel insights into iNTS disease pathogenesis. METHODS AND ANALYSIS This double-blind, safety and dose-escalation study will randomise 40-80 healthy UK participants aged 18-50 to receive oral challenge with one of two strains of S. Typhimurium belonging to the ST19 (strain 4/74) or ST313 (strain D23580) lineages. 4/74 is a global strain often associated with diarrhoeal illness predominantly in high-income settings, while D23580 is an archetypal strain representing invasive disease-causing isolates found in SSA. The primary objective is to determine the minimum infectious dose (colony-forming unit) required for 60%-75% of participants to develop clinical or microbiological features of systemic salmonellosis. Secondary endpoints are to describe and compare the clinical, microbiological and immunological responses following challenge. Dose escalation or de-escalation will be undertaken by continual-reassessment methodology and limited within prespecified safety thresholds. Exploratory objectives are to describe mechanisms of iNTS virulence, identify putative immune correlates of protection and describe host-pathogen interactions in response to infection. ETHICS AND DISSEMINATION Ethical approval has been obtained from the NHS Health Research Authority (London-Fulham Research Ethics Committee 21/PR/0051; IRAS Project ID 301659). The study findings will be disseminated in international peer-reviewed journals and presented at national/international stakeholder meetings. Study outcome summaries will be provided to both funders and participants. TRIAL REGISTRATION NUMBER NCT05870150.
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Affiliation(s)
- Christopher Smith
- Department of Infectious Disease, Imperial College London, London, UK
| | - Emma Smith
- Department of Infectious Disease, Imperial College London, London, UK
| | - Anna Rydlova
- Department of Infectious Disease, Imperial College London, London, UK
| | - Robert Varro
- Department of Infectious Disease, Imperial College London, London, UK
| | - Jay C D Hinton
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Melita A Gordon
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Southern Region, Malawi
| | | | - Xinxue Liu
- Oxford Vaccine Group, Department of Paediatrics, Oxford University, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, Oxford University, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Christopher Chiu
- Department of Infectious Disease, Imperial College London, London, UK
| | - Graham S Cooke
- Department of Infectious Disease, Imperial College London, London, UK
| | - Malick M Gibani
- Department of Infectious Disease, Imperial College London, London, UK
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21
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Haldar R, Dhar A, Ganguli D, Chakraborty S, Pal A, Banik G, Miyoshi SI, Das S. A candidate glycoconjugate vaccine induces protective antibodies in the serum and intestinal secretions, antibody recall response and memory T cells and protects against both typhoidal and non-typhoidal Salmonella serovars. Front Immunol 2024; 14:1304170. [PMID: 38264668 PMCID: PMC10804610 DOI: 10.3389/fimmu.2023.1304170] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 12/18/2023] [Indexed: 01/25/2024] Open
Abstract
Human Salmonella infections pose significant public health challenges globally, primarily due to low diagnostic yield of systemic infections, emerging and expanding antibiotic resistance of both the typhoidal and non-typhoidal Salmonella strains and the development of asymptomatic carrier state that functions as a reservoir of infection in the community. The limited long-term efficacy of the currently licensed typhoid vaccines, especially in smaller children and non-availability of vaccines against other Salmonella serovars necessitate active research towards developing a multivalent vaccine with wider coverage of protection against pathogenic Salmonella serovars. We had earlier reported immunogenicity and protective efficacy of a subunit vaccine containing a recombinant outer membrane protein (T2544) of Salmonella Typhi in a mouse model. This was achieved through the robust induction of serum IgG, mucosal secretory IgA and Salmonella-specific cytotoxic T cells as well as memory B and T cell response. Here, we report the development of a glycoconjugate vaccine, containing high molecular weight complexes of Salmonella Typhimurium O-specific polysaccharide (OSP) and recombinant T2544 that conferred simultaneous protection against S. Typhi, S. Paratyphi, S. Typhimurium and cross-protection against S. enteritidis in mice. Our findings corroborate with the published studies that suggested the potential of Salmonella OSP as a vaccine antigen. The role of serum antibodies in vaccine-mediated protection is suggested by rapid seroconversion with high titers of serum IgG and IgA, persistently elevated titers after primary immunization along with a strong antibody recall response with higher avidity serum IgG against both OSP and T2544 and significantly raised SBA titers of both primary and secondary antibodies against different Salmonella serovars. Elevated intestinal secretory IgA and bacterial motility inhibition by the secretory antibodies supported their role as well in vaccine-induced protection. Finally, robust induction of T effector memory response indicates long term efficacy of the candidate vaccine. The above findings coupled with protection of vaccinated animals against multiple clinical isolates confirm the suitability of OSP-rT2544 as a broad-spectrum candidate subunit vaccine against human infection due to typhoidal and non-typhoidal Salmonella serovars.
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Affiliation(s)
- Risha Haldar
- Division of Clinical Medicine, Indian Council of Medical Research (ICMR)-National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Amlanjyoti Dhar
- Division of Molecular Biology and Genomics, International Institute of Innovation and Technology (I3T), Kolkata, India
| | - Debayan Ganguli
- Department of Infectious Diseases, Washington University School of Medicine at St. Louis, St. Louis, MO, United States
| | - Suparna Chakraborty
- Division of Clinical Medicine, Indian Council of Medical Research (ICMR)-National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Ananda Pal
- Division of Clinical Medicine, Indian Council of Medical Research (ICMR)-National Institute of Cholera and Enteric Diseases, Kolkata, India
| | | | - Shin-ichi Miyoshi
- Division of Medicine, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Santasabuj Das
- Division of Clinical Medicine, Indian Council of Medical Research (ICMR)-National Institute of Cholera and Enteric Diseases, Kolkata, India
- Division of Biological Science, Indian Council of Medical Research (ICMR)-National Institute of Occupational Health, Ahmedabad, India
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Alugupalli KR. TLR4 Ligands in Typhoid Vi Polysaccharide Subunit Vaccines Contribute to Immunogenicity. Immunohorizons 2024; 8:29-34. [PMID: 38180344 PMCID: PMC10832388 DOI: 10.4049/immunohorizons.2300085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 12/11/2023] [Indexed: 01/06/2024] Open
Abstract
Activation of B cells and T cells requires the engagement of costimulatory signaling pathways in addition to Ag receptor signaling for efficient immune responses. None of the typhoid Vi polysaccharide (ViPS) subunit vaccines contains adjuvants that could activate costimulatory signaling pathways, yet these vaccines are very immunogenic. I hypothesized that residual TLR ligands present in the ViPS preparation used for making typhoid subunit vaccines account for the robust immune response generated by these vaccines. I show the presence of endotoxin, a potent agonist of TLR4, in ViPS preparations and ViPS vaccines. Furthermore, I found that ViPS obtained from various sources induces the production of proinflammatory cytokines such as IL-6 from mouse peritoneal exudate cells. Unconjugated and tetanus toxoid-conjugated ViPS vaccines activate human and mouse TLR4. Mice deficient in TLR4 or the signaling adaptors MyD88 and Trif (Toll/IL-1R domain-containing adapter inducing IFN-β) are severely impaired in generating anti-ViPS responses to these vaccines. Elimination of the TLR4 agonist in ViPS preparation resulted in the loss of immunogenicity, and addition of lipid A, a known TLR4 agonist, restored the immunogenicity. These data highlight the importance of associated TLR ligands in the immunogenicity of ViPS subunit vaccines.
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Affiliation(s)
- Kishore R. Alugupalli
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
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23
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Tadesse BT, Keddy KH, Rickett NY, Zhusupbekova A, Poudyal N, Lawley T, Osman M, Dougan G, Kim JH, Lee JS, Jeon HJ, Marks F. Vaccination to Reduce Antimicrobial Resistance Burden-Data Gaps and Future Research. Clin Infect Dis 2023; 77:S597-S607. [PMID: 38118013 PMCID: PMC10732565 DOI: 10.1093/cid/ciad562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023] Open
Abstract
Antimicrobial resistance (AMR) poses an immediate danger to global health. If unaddressed, the current upsurge in AMR threatens to reverse the achievements in reducing the infectious disease-associated mortality and morbidity associated with antimicrobial treatment. Consequently, there is an urgent need for strategies to prevent or slow the progress of AMR. Vaccines potentially contribute both directly and indirectly to combating AMR. Modeling studies have indicated significant gains from vaccination in reducing AMR burdens for specific pathogens, reducing mortality/morbidity, and economic loss. However, quantifying the real impact of vaccines in these reductions is challenging because many of the study designs used to evaluate the contribution of vaccination programs are affected by significant background confounding, and potential selection and information bias. Here, we discuss challenges in assessing vaccine impact to reduce AMR burdens and suggest potential approaches for vaccine impact evaluation nested in vaccine trials.
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Affiliation(s)
- Birkneh Tilahun Tadesse
- International Vaccine Institute, Seoul, Republic of Korea
- Division of Clinical Pharmacology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
- Center for Innovative Drug Development and Therapeutic Trials for Africa, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | | | | | | | - Nimesh Poudyal
- International Vaccine Institute, Seoul, Republic of Korea
| | - Trevor Lawley
- Wellcome Sanger Institute and Microbiotica, Cambridge, United Kingdom
| | - Majdi Osman
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
| | - Gordon Dougan
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
| | - Jerome H Kim
- International Vaccine Institute, Seoul, Republic of Korea
- Seoul National University, College of Natural Sciences, Seoul, Republic of Korea
| | - Jung-Seok Lee
- International Vaccine Institute, Seoul, Republic of Korea
| | - Hyon Jin Jeon
- International Vaccine Institute, Seoul, Republic of Korea
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
- Madagascar Institute for Vaccine Research, University of Antananarivo, Antananarivo, Madagascar
| | - Florian Marks
- International Vaccine Institute, Seoul, Republic of Korea
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
- Madagascar Institute for Vaccine Research, University of Antananarivo, Antananarivo, Madagascar
- Heidelberg Institute of Global Health, University of Heidelberg, Heidelberg, Germany
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Meiring JE, Khanam F, Basnyat B, Charles RC, Crump JA, Debellut F, Holt KE, Kariuki S, Mugisha E, Neuzil KM, Parry CM, Pitzer VE, Pollard AJ, Qadri F, Gordon MA. Typhoid fever. Nat Rev Dis Primers 2023; 9:71. [PMID: 38097589 DOI: 10.1038/s41572-023-00480-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/06/2023] [Indexed: 12/18/2023]
Abstract
Typhoid fever is an invasive bacterial disease associated with bloodstream infection that causes a high burden of disease in Africa and Asia. Typhoid primarily affects individuals ranging from infants through to young adults. The causative organism, Salmonella enterica subsp. enterica serovar Typhi is transmitted via the faecal-oral route, crossing the intestinal epithelium and disseminating to systemic and intracellular sites, causing an undifferentiated febrile illness. Blood culture remains the practical reference standard for diagnosis of typhoid fever, where culture testing is available, but novel diagnostic modalities are an important priority under investigation. Since 2017, remarkable progress has been made in defining the global burden of both typhoid fever and antimicrobial resistance; in understanding disease pathogenesis and immunological protection through the use of controlled human infection; and in advancing effective vaccination programmes through strategic multipartner collaboration and targeted clinical trials in multiple high-incidence priority settings. This Primer thus offers a timely update of progress and perspective on future priorities for the global scientific community.
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Affiliation(s)
- James E Meiring
- Division of Clinical Medicine, School of Medicine and Population Health, University of Sheffield, Sheffield, UK
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi
| | - Farhana Khanam
- International Centre for Diarrhoel Disease Research, Dhaka, Bangladesh
| | - Buddha Basnyat
- Oxford University Clinical Research Unit, Kathmandu, Nepal
| | - Richelle C Charles
- Massachusetts General Hospital, Harvard Medical School, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - John A Crump
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | | | - Kathryn E Holt
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Samuel Kariuki
- Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Emmanuel Mugisha
- Center for Vaccine Innovation and Access, PATH, Seattle, WA, USA
| | - Kathleen M Neuzil
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Christopher M Parry
- Department of Clinical Sciences and Education, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Virginia E Pitzer
- Department of Epidemiology of Microbial Diseases and Public Health Modelling Unit, Yale School of Public Health, Yale University, New Haven, CT, USA
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Firdausi Qadri
- International Centre for Diarrhoel Disease Research, Dhaka, Bangladesh
| | - Melita A Gordon
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi.
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK.
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Abo YN, Jamrozik E, McCarthy JS, Roestenberg M, Steer AC, Osowicki J. Strategic and scientific contributions of human challenge trials for vaccine development: facts versus fantasy. THE LANCET. INFECTIOUS DISEASES 2023; 23:e533-e546. [PMID: 37573871 DOI: 10.1016/s1473-3099(23)00294-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/24/2023] [Accepted: 04/26/2023] [Indexed: 08/15/2023]
Abstract
The unprecedented speed of delivery of SARS-CoV-2 pandemic vaccines has redefined the limits for all vaccine development. Beyond the aspirational 100-day timeline for tomorrow's hypothetical pandemic vaccines, there is a sense of optimism that development of other high priority vaccines can be accelerated. Early in the COVID-19 pandemic, an intense and polarised academic and public discourse arose concerning the role of human challenge trials for vaccine development. A case was made for human challenge trials as a powerful tool to establish early proof-of-concept of vaccine efficacy in humans, inform vaccine down selection, and address crucial knowledge gaps regarding transmission, pathogenesis, and immune protection. We review the track record of human challenge trials contributing to the development of vaccines for 19 different pathogens and discuss relevant limitations, barriers, and pitfalls. This Review also highlights opportunities for efforts to broaden the scope and boost the effects of human challenge trials, to accelerate all vaccine development.
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Affiliation(s)
- Yara-Natalie Abo
- Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, VIC, Australia; Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia; Infectious Diseases Unit, Department of General Medicine, Royal Children's Hospital Melbourne, Parkville, VIC, Australia.
| | - Euzebiusz Jamrozik
- Ethox and Pandemic Sciences Institute, Nuffield Department of Population Health, University of Oxford, Oxford, UK; Monash-WHO Collaborating Centre for Bioethics, Monash University, Melbourne, VIC, Australia
| | - James S McCarthy
- Department of Infectious Diseases, The University of Melbourne, Parkville, VIC, Australia; Victorian Infectious Diseases Services, Royal Melbourne Hospital, Parkville, VIC, Australia
| | - Meta Roestenberg
- Controlled Human Infections Center, Leiden University Medical Center, Leiden, Netherlands
| | - Andrew C Steer
- Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, VIC, Australia; Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia; Infectious Diseases Unit, Department of General Medicine, Royal Children's Hospital Melbourne, Parkville, VIC, Australia
| | - Joshua Osowicki
- Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, VIC, Australia; Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia; Infectious Diseases Unit, Department of General Medicine, Royal Children's Hospital Melbourne, Parkville, VIC, Australia
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Barton A, Hill J, O'Connor D, Jones C, Jones E, Camara S, Shrestha S, Jin C, Gibani MM, Dobinson HC, Waddington C, Darton TC, Blohmke CJ, Pollard AJ. Early transcriptional responses to human enteric fever challenge. Infect Immun 2023; 91:e0010823. [PMID: 37725060 PMCID: PMC10581002 DOI: 10.1128/iai.00108-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 06/29/2023] [Indexed: 09/21/2023] Open
Abstract
Enteric fever, caused by oral infection with typhoidal Salmonella serovars, presents as a non-specific febrile illness preceded by an incubation period of 5 days or more. The enteric fever human challenge model provides a unique opportunity to investigate the innate immune response during this incubation period, and how this response is altered by vaccination with the Vi polysaccharide or conjugate vaccine. We find that on the same day as ingestion of typhoidal Salmonella, there is already evidence of an immune response, with 199 genes upregulated in the peripheral blood transcriptome 12 hours post-challenge (false discovery rate <0.05). Gene sets relating to neutrophils, monocytes, and innate immunity were over-represented (false discovery rate <0.05). Estimating cell proportions from gene expression data suggested a possible increase in activated monocytes 12 hours post-challenge (P = 0.036, paired Wilcoxon signed-rank test). Furthermore, plasma TNF-α rose following exposure (P = 0.011, paired Wilcoxon signed-rank test). There were no significant differences in gene expression (false discovery rate <0.05) in the 12 hours response between those who did and did not subsequently develop clinical or blood culture confirmed enteric fever or between vaccination groups. Together, these results demonstrate early perturbation of the peripheral blood transcriptome after enteric fever challenge and provide initial insight into early mechanisms of protection.
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Affiliation(s)
- Amber Barton
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Jennifer Hill
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Daniel O'Connor
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Claire Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Elizabeth Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Susana Camara
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Sonu Shrestha
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Celina Jin
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Pathology, Royal Melbourne Hospital, Melbourne, Australia
- Infectious Diseases and Immune Defence Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Malick M. Gibani
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Infectious Disease, Imperial College, London, United Kingdom
| | - Hazel C. Dobinson
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Claire Waddington
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Infectious Disease, Imperial College, London, United Kingdom
| | - Thomas C. Darton
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Infection, Immunity and Cardiovascular Disease and The Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
| | - Christoph J. Blohmke
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Andrew J. Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
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LeBoa C, Shrestha S, Shakya J, Naga SR, Shrestha S, Shakya M, Yu AT, Shrestha R, Vaidya K, Katuwal N, Aiemjoy K, Bogoch II, Uzzell CB, Garrett DO, Luby SP, Andrews JR, Tamrakar D. Environmental sampling for typhoidal Salmonellas in household and surface waters in Nepal identifies potential transmission pathways. PLoS Negl Trop Dis 2023; 17:e0011341. [PMID: 37851667 PMCID: PMC10615262 DOI: 10.1371/journal.pntd.0011341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 10/30/2023] [Accepted: 09/06/2023] [Indexed: 10/20/2023] Open
Abstract
INTRODUCTION Salmonella Typhi and Salmonella Paratyphi, fecal-oral transmitted bacterium, have temporally and geographically heterogeneous pathways of transmission. Previous work in Kathmandu, Nepal implicated stone waterspouts as a dominant transmission pathway after 77% of samples tested positive for Salmonella Typhi and 70% for Salmonella Paratyphi. Due to a falling water table, these spouts no longer provide drinking water, but typhoid fever persists, and the question of the disease's dominant pathway of transmission remains unanswered. METHODS We used environmental surveillance to detect Salmonella Typhi and Salmonella Paratyphi A DNA from potential sources of transmission. We collected 370, 1L drinking water samples from a population-based random sample of households in the Kathmandu and Kavre Districts of Nepal between February and October 2019. Between November 2019 and July 2021, we collected 380, 50mL river water samples from 19 sentinel sites on a monthly interval along the rivers leading through the Kathmandu and Kavre Districts. We processed drinking water samples using a single qPCR and processed river water samples using differential centrifugation and qPCR at 0 and after 16 hours of liquid culture enrichment. A 3-cycle threshold (Ct) decrease of Salmonella Typhi or Salmonella Paratyphi, pre- and post-enrichment, was used as evidence of growth. We also performed structured observations of human-environment interactions to understand pathways of potential exposure. RESULTS Among 370 drinking water samples, Salmonella Typhi was detected in 7 samples (1.8%) and Salmonella Paratyphi A was detected in 4 (1.0%) samples. Among 380 river water samples, Salmonella Typhi was detected in 171 (45%) and Salmonella Paratyphi A was detected in 152 (42%) samples. Samples located upstream of the Kathmandu city center were positive for Salmonella Typhi 12% of the time while samples from locations in and downstream were positive 58% and 67% of the time respectively. Individuals were observed bathing, washing clothes, and washing vegetables in the rivers. IMPLICATIONS These results suggest that drinking water was not the dominant pathway of transmission of Salmonella Typhi and Salmonella Paratyphi A in the Kathmandu Valley in 2019. The high degree of river water contamination and its use for washing vegetables raises the possibility that river systems represent an important source of typhoid exposure in Kathmandu.
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Affiliation(s)
- Christopher LeBoa
- Stanford University, Division of Infectious Diseases and Geographic Medicine, Stanford, California, United States of America
- University of California Berkeley, Department of Environmental Health Sciences, Berkeley, California, United States of America
| | - Sneha Shrestha
- Research and Development Division, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
| | - Jivan Shakya
- Institute for Research in Science and Technology, Lalitpur, Nepal
| | - Shiva Ram Naga
- Research and Development Division, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
- Center for Infectious Disease Research and Surveillance, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
| | - Sony Shrestha
- Research and Development Division, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
| | - Mudita Shakya
- Research and Development Division, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
| | - Alexander T. Yu
- Stanford University, Division of Infectious Diseases and Geographic Medicine, Stanford, California, United States of America
| | - Rajeev Shrestha
- Research and Development Division, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
- Center for Infectious Disease Research and Surveillance, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
| | - Krista Vaidya
- Research and Development Division, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
| | - Nishan Katuwal
- Research and Development Division, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
- Center for Infectious Disease Research and Surveillance, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
| | - Kristen Aiemjoy
- University of California Davis, Division of Public Health Sciences, California, United States of America
- Mahidol University Faculty of Tropical Medicine, Department of Microbiology and Immunology, Bangkok, Thailand
| | - Isaac I. Bogoch
- Toronto General Hospital, Division of Infectious Diseases, Toronto, Canada, and Department of Medicine, University of Toronto, Toronto Canada
| | - Christopher B. Uzzell
- Imperial College London, School of Public Health, Norfolk Place, London, United Kingdom
| | - Denise O. Garrett
- Sabin Vaccine Institute, Applied Epidemiology Section, Washington, DC, United States of America
| | - Stephen P. Luby
- Stanford University, Division of Infectious Diseases and Geographic Medicine, Stanford, California, United States of America
| | - Jason R. Andrews
- Stanford University, Division of Infectious Diseases and Geographic Medicine, Stanford, California, United States of America
| | - Dipesh Tamrakar
- Research and Development Division, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
- Center for Infectious Disease Research and Surveillance, Dhulikhel Hospital Kathmandu University Hospital, Kavre, Nepal
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Ouedraogo A, Diarra A, Nébié I, Barry N, Kabore JM, Tiono AB, Datta S, Liang Y, Mayo I, Oshinsky JJ, Tracy JK, Girmay T, Pasetti MF, Jamka LP, Neuzil KM, Sirima SB, Laurens MB. Durable Anti-Vi IgG and IgA Antibody Responses in 15-Month-Old Children Vaccinated With Typhoid Conjugate Vaccine in Burkina Faso. J Pediatric Infect Dis Soc 2023; 12:513-518. [PMID: 37589596 PMCID: PMC10533206 DOI: 10.1093/jpids/piad058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Accepted: 08/15/2023] [Indexed: 08/18/2023]
Abstract
We assessed anti-Vi IgG/IgA responses to typhoid conjugate vaccine (TCV) in children enrolled in a double-blind randomized controlled, phase 2 trial in Burkina Faso. Anti-Vi IgG seroconversion and anti-Vi IgA titers were higher in TCV than control recipients at 30-35 months post-vaccination. TCV induces durable immunity in Burkinabe children vaccinated at 15 months.
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Affiliation(s)
| | - Amidou Diarra
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | - Issa Nébié
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | - Nouhoun Barry
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | | | - Alfred B Tiono
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | - Shrimati Datta
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Yuanyuan Liang
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Ifayet Mayo
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Jennifer J Oshinsky
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - J Kathleen Tracy
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Tsion Girmay
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Marcela F Pasetti
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Leslie P Jamka
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kathleen M Neuzil
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | | | - Matthew B Laurens
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Dula D, Morton B, Chikaonda T, Chirwa AE, Nsomba E, Nkhoma V, Ngoliwa C, Sichone S, Galafa B, Tembo G, Chaponda M, Toto N, Kamng'ona R, Makhaza L, Muyaya A, Thole F, Kudowa E, Howard A, Kenny-Nyazika T, Ndaferankhande J, Mkandawire C, Chiwala G, Chimgoneko L, Banda NPK, Rylance J, Ferreira D, Jambo K, Henrion MYR, Gordon SB. Effect of 13-valent pneumococcal conjugate vaccine on experimental carriage of Streptococcus pneumoniae serotype 6B in Blantyre, Malawi: a randomised controlled trial and controlled human infection study. THE LANCET. MICROBE 2023; 4:e683-e691. [PMID: 37659418 PMCID: PMC10469263 DOI: 10.1016/s2666-5247(23)00178-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 06/01/2023] [Accepted: 06/02/2023] [Indexed: 09/04/2023]
Abstract
BACKGROUND The effect of childhood pneumococcal conjugate vaccine implementation in Malawi is threatened by absence of herd effect. There is persistent vaccine-type pneumococcal carriage in both vaccinated children and the wider community. We aimed to use a human infection study to measure 13-valent pneumococcal conjugate vaccine (PCV13) efficacy against pneumococcal carriage. METHODS We did a double-blind, parallel-arm, randomised controlled trial investigating the efficacy of PCV13 or placebo against experimental pneumococcal carriage of Streptococcus pneumoniae serotype 6B (strain BHN418) among healthy adults (aged 18-40 years) from Blantyre, Malawi. We randomly assigned participants (1:1) to receive PCV13 or placebo. PCV13 and placebo doses were prepared by an unmasked pharmacist to maintain research team and participant masking with identification only by a randomisation identification number and barcode. 4 weeks after receiving either PCV13 or placebo, participants were challenged with 20 000 colony forming units (CFUs) per naris, 80 000 CFUs per naris, or 160 000 CFUs per naris by intranasal inoculation. The primary endpoint was experimental pneumococcal carriage, established by culture of nasal wash at 2, 7, and 14 days. Vaccine efficacy was estimated per protocol by means of a log-binomial model adjusting for inoculation dose. The trial is registered with the Pan African Clinical Trials Registry, PACTR202008503507113, and is now closed. FINDINGS Recruitment commenced on April 27, 2021 and the final visit was completed on Sept 12, 2022. 204 participants completed the study protocol (98 PCV13, 106 placebo). There were lower carriage rates in the vaccine group at all three inoculation doses (0 of 21 vs two [11%] of 19 at 20 000 CFUs per naris; six [18%] of 33 vs 12 [29%] of 41 at 80 000 CFUs per naris, and four [9%] of 44 vs 16 [35%] of 46 at 160 000 CFUs per naris). The overall carriage rate was lower in the vaccine group compared with the placebo group (ten [10%] of 98 vs 30 [28%] of 106; Fisher's p value=0·0013) and the vaccine efficacy against carriage was estimated at 62·4% (95% CI 27·7-80·4). There were no severe adverse events related to vaccination or inoculation of pneumococci. INTERPRETATION This is, to our knowledge, the first human challenge study to test the efficacy of a pneumococcal vaccine against pneumococcal carriage in Africa, which can now be used to establish vaccine-induced correlates of protection and compare alternative strategies to prevent pneumococcal carriage. This powerful tool could lead to new means to enhance reduction in pneumococcal carriage after vaccination. FUNDING Wellcome Trust.
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Affiliation(s)
- Dingase Dula
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
| | - Ben Morton
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK; Critical Care Department, Liverpool University Hospitals NHS Foundation Trust, Liverpool, UK.
| | | | | | - Edna Nsomba
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
| | | | - Clara Ngoliwa
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi; Department of Medicine, Queen Elizabeth Central Hospital, Blantyre, Malawi
| | - Simon Sichone
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
| | | | - Godwin Tembo
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
| | | | - Neema Toto
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
| | | | - Lumbani Makhaza
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
| | - Alfred Muyaya
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
| | - Faith Thole
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
| | | | - Ashleigh Howard
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Tinashe Kenny-Nyazika
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | | | | | - Gift Chiwala
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
| | | | - Ndaziona P K Banda
- Department of Medicine, Queen Elizabeth Central Hospital, Blantyre, Malawi; School of Medicine, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Jamie Rylance
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
| | - Daniela Ferreira
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK; Department of Paediatrics, University of Oxford, Oxford, UK
| | - Kondwani Jambo
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi; Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Marc Y R Henrion
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi; Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Stephen B Gordon
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi; Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
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Zhu H, Chelysheva I, Cross DL, Blackwell L, Jin C, Gibani MM, Jones E, Hill J, Trück J, Kelly DF, Blohmke CJ, Pollard AJ, O’Connor D. Molecular correlates of vaccine-induced protection against typhoid fever. J Clin Invest 2023; 133:e169676. [PMID: 37402153 PMCID: PMC10425215 DOI: 10.1172/jci169676] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 06/27/2023] [Indexed: 07/06/2023] Open
Abstract
BACKGROUNDTyphoid fever is caused by the Gram-negative bacterium Salmonella enterica serovar Typhi and poses a substantial public health burden worldwide. Vaccines have been developed based on the surface Vi-capsular polysaccharide of S. Typhi; these include a plain-polysaccharide-based vaccine, ViPS, and a glycoconjugate vaccine, ViTT. To understand immune responses to these vaccines and their vaccine-induced immunological protection, molecular signatures were analyzed using bioinformatic approaches.METHODSBulk RNA-Seq data were generated from blood samples obtained from adult human volunteers enrolled in a vaccine trial, who were then challenged with S. Typhi in a controlled human infection model (CHIM). These data were used to conduct differential gene expression analyses, gene set and modular analyses, B cell repertoire analyses, and time-course analyses at various post-vaccination and post-challenge time points between participants receiving ViTT, ViPS, or a control meningococcal vaccine.RESULTSTranscriptomic responses revealed strong differential molecular signatures between the 2 typhoid vaccines, mostly driven by the upregulation in humoral immune signatures, including selective usage of immunoglobulin heavy chain variable region (IGHV) genes and more polarized clonal expansions. We describe several molecular correlates of protection against S. Typhi infection, including clusters of B cell receptor (BCR) clonotypes associated with protection, with known binders of Vi-polysaccharide among these.CONCLUSIONThe study reports a series of contemporary analyses that reveal the transcriptomic signatures after vaccination and infectious challenge, while identifying molecular correlates of protection that may inform future vaccine design and assessment.TRIAL REGISTRATIONClinicalTrials.gov NCT02324751.
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Affiliation(s)
- Henderson Zhu
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Irina Chelysheva
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Deborah L. Cross
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Luke Blackwell
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Celina Jin
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Malick M. Gibani
- Department of Infectious Disease, Imperial College London, St Mary’s Campus, London, United Kingdom
| | - Elizabeth Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Jennifer Hill
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Johannes Trück
- Division of Immunology, University Children’s Hospital Zurich, Zurich, Switzerland
| | - Dominic F. Kelly
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Christoph J. Blohmke
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Andrew J. Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Daniel O’Connor
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
- NIHR Oxford Biomedical Research Centre and Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
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Meiring JE, Johnston PI. Typhoid Fever: A Reduction and a Resurgence. Am J Trop Med Hyg 2023; 109:219-220. [PMID: 37308101 PMCID: PMC10397432 DOI: 10.4269/ajtmh.23-0286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 05/09/2023] [Indexed: 06/14/2023] Open
Affiliation(s)
- James E. Meiring
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Peter I. Johnston
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
- Malawi Liverpool Wellcome Research Programme, Blantyre, Malawi
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32
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Kelly M, Mandlik A, Charles RC, Verma S, Calderwood SB, Leung DT, Biswas R, Islam K, Kamruzzaman M, Chowdhury F, Khanam F, Vann WF, Khan AI, Bhuiyan TR, Qadri F, Vortherms AR, Kaminski R, Kováč P, Xu P, Ryan ET. Development of Shigella conjugate vaccines targeting Shigella flexneri 2a and S. flexneri 3a using a simple platform-approach conjugation by squaric acid chemistry. Vaccine 2023; 41:4967-4977. [PMID: 37400283 PMCID: PMC10529421 DOI: 10.1016/j.vaccine.2023.06.052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 07/05/2023]
Abstract
There is a need for vaccines effective against shigella infection in young children in resource-limited areas. Protective immunity against shigella infection targets the O-specific polysaccharide (OSP) component of lipopolysaccharide. Inducing immune responses to polysaccharides in young children can be problematic, but high level and durable responses can be induced by presenting polysaccharides conjugated to carrier proteins. An effective shigella vaccine will need to be multivalent, targeting the most common global species and serotypes such as Shigella flexneri 2a, S. flexneri 3a, S. flexneri 6, and S. sonnei. Here we report the development of shigella conjugate vaccines (SCV) targeting S. flexneri 2a (SCV-Sf2a) and 3a (SCV-Sf3a) using squaric acid chemistry to result in single point sun-burst type display of OSP from carrier protein rTTHc, a 52 kDa recombinant protein fragment of the heavy chain of tetanus toxoid. We confirmed structure and demonstrated that these conjugates were recognized by serotype-specific monoclonal antibodies and convalescent sera of humans recovering from shigellosis in Bangladesh, suggesting correct immunological display of OSP. We vaccinated mice and found induction of serotype-specific OSP and LPS IgG responses, as well as rTTHc-specific IgG responses. Vaccination induced serotype-specific bactericidal antibody responses against S. flexneri, and vaccinated animals were protected against keratoconjunctivitis (Sereny test) and intraperitoneal challenge with virulent S. flexneri 2a and 3a, respectively. Our results support further development of this platform conjugation technology in the development of shigella conjugate vaccines for use in resource-limited settings.
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Affiliation(s)
- Meagan Kelly
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, USA
| | - Anjali Mandlik
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, USA
| | - Richelle C Charles
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, USA; Department of Medicine, Harvard Medical School, Boston, MA, USA; Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Smriti Verma
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, USA
| | - Stephen B Calderwood
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, USA; Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Daniel T Leung
- Division of Infectious Diseases, University of Utah, Salt Lake City, Utah, USA
| | - Rajib Biswas
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Kamrul Islam
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Mohammad Kamruzzaman
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Fahima Chowdhury
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Farhana Khanam
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Willie F Vann
- Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Ashraful Islam Khan
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Taufiqur Rahman Bhuiyan
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Firdausi Qadri
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Anthony R Vortherms
- Department of Diarrheal Disease Research, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Bethesda, MD, USA
| | - Robert Kaminski
- Department of Diarrheal Disease Research, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Bethesda, MD, USA
| | - Pavol Kováč
- NIDDK, LBC, National Institutes of Health, Bethesda, MD, USA
| | - Peng Xu
- NIDDK, LBC, National Institutes of Health, Bethesda, MD, USA
| | - Edward T Ryan
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, USA; Department of Medicine, Harvard Medical School, Boston, MA, USA; Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
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Rutanga JP, de Block T, Cuypers WL, Cafmeyer J, Peeters M, Umumararungu E, Ngabonziza JCS, Rucogoza A, Vandenberg O, Martiny D, Dusabe A, Nkubana T, Dougan G, Muvunyi CM, Mwikarago IE, Jacobs J, Deborggraeve S, Van Puyvelde S. Salmonella Typhi whole genome sequencing in Rwanda shows a diverse historical population with recent introduction of haplotype H58. PLoS Negl Trop Dis 2023; 17:e0011285. [PMID: 37327220 DOI: 10.1371/journal.pntd.0011285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 04/04/2023] [Indexed: 06/18/2023] Open
Abstract
Salmonella enterica serovar Typhi (S. Typhi) is the cause of typhoid fever, presenting high rates of morbidity and mortality in low- and middle-income countries. The H58 haplotype shows high levels of antimicrobial resistance (AMR) and is the dominant S. Typhi haplotype in endemic areas of Asia and East sub-Saharan Africa. The situation in Rwanda is currently unknown and therefore to reveal the genetic diversity and AMR of S. Typhi in Rwanda, 25 historical (1984-1985) and 26 recent (2010-2018) isolates from Rwanda were analysed using whole genome sequencing (WGS). WGS was locally implemented using Illumina MiniSeq and web-based analysis tools, thereafter complemented with bioinformatic approaches for more in-depth analyses. Whereas historical S. Typhi isolates were found to be fully susceptible to antimicrobials and show a diversity of genotypes, i.e 2.2.2, 2.5, 3.3.1 and 4.1; the recent isolates showed high AMR rates and were predominantly associated with genotype 4.3.1.2 (H58, 22/26; 84,6%), possibly resulting from a single introduction in Rwanda from South Asia before 2010. We identified practical challenges for the use of WGS in endemic regions, including a high cost for shipment of molecular reagents and lack of high-end computational infrastructure for the analyses, but also identified WGS to be feasible in the studied setting and giving opportunity for synergy with other programs.
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Affiliation(s)
- Jean Pierre Rutanga
- College of Science and Technology, University of Rwanda, Kigali, Rwanda
- Institute of Tropical Medicine, Antwerp, Belgium
- Department of Microbiology, Immunology and Transplantation, KU Leuven, Leuven, Belgium
| | | | - Wim L Cuypers
- Institute of Tropical Medicine, Antwerp, Belgium
- Department of Computer Science, University of Antwerp, Antwerp, Belgium
| | | | | | | | - Jean Claude S Ngabonziza
- Rwanda Biomedical Centre, Kigali, Rwanda
- Department of Clinical Biology, University of Rwanda, Kigali, Rwanda
| | | | - Olivier Vandenberg
- Department of Microbiology, Laboratoire Hospitalier Universitaire de Bruxelles (LHUB-ULB), Hôpital Erasme-Cliniques universitaires de Bruxelles, Université Libre de Bruxelles, Brussels, Belgium
| | - Delphine Martiny
- Department of Microbiology, Laboratoire des Hôpitaux Universitaires de Bruxelles - Universitaire Laboratorium Brussel (LHUB-ULB), Brussels, Belgium
- National Reference Centre for Campylobacter, CHU Saint-Pierre, Brussels, Belgium
- Faculté de Médecine et Pharmacie, Université de Mons (UMONS), Mons, Belgium
| | - Angélique Dusabe
- Centre Hospitalier Universtaire de Kigali (CHUK), Kigali, Rwanda
| | | | - Gordon Dougan
- Department of Medicine, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, United Kingdom
| | | | | | - Jan Jacobs
- Institute of Tropical Medicine, Antwerp, Belgium
- Department of Microbiology, Immunology and Transplantation, KU Leuven, Leuven, Belgium
| | | | - Sandra Van Puyvelde
- Institute of Tropical Medicine, Antwerp, Belgium
- Department of Medicine, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, United Kingdom
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
- Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, Antwerp, Belgium
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34
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Gordon SB, Sichone S, Chirwa AE, Hazenberg P, Kafuko Z, Ferreira DM, Flynn J, Fortune S, Balasingam S, Biagini GA, McShane H, Mwandumba HC, Jambo K, Dheda K, Raj Sharma N, Robertson BD, Walker NF, Morton B. Practical considerations for a TB controlled human infection model (TB-CHIM); the case for TB-CHIM in Africa, a systematic review of the literature and report of 2 workshop discussions in UK and Malawi. Wellcome Open Res 2023; 8:71. [PMID: 37007907 PMCID: PMC10064019 DOI: 10.12688/wellcomeopenres.18767.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2023] [Indexed: 06/23/2023] Open
Abstract
Background: Tuberculosis (TB) remains a major challenge in many domains including diagnosis, pathogenesis, prevention, treatment, drug resistance and long-term protection of the public health by vaccination. A controlled human infection model (CHIM) could potentially facilitate breakthroughs in each of these domains but has so far been considered impossible owing to technical and safety concerns. Methods: A systematic review of mycobacterial human challenge studies was carried out to evaluate progress to date, best possible ways forward and challenges to be overcome. We searched MEDLINE (1946 to current) and CINAHL (1984 to current) databases; and Google Scholar to search citations in selected manuscripts. The final search was conducted 3 rd February 2022. Inclusion criteria: adults ≥18 years old; administration of live mycobacteria; and interventional trials or cohort studies with immune and/or microbiological endpoints. Exclusion criteria: animal studies; studies with no primary data; no administration of live mycobacteria; retrospective cohort studies; case-series; and case-reports. Relevant tools (Cochrane Collaboration for RCTs and Newcastle-Ottawa Scale for non-randomised studies) were used to assess risk of bias and present a narrative synthesis of our findings. Results: The search identified 1,388 titles for review; of these 90 were reviewed for inclusion; and 27 were included. Of these, 15 were randomised controlled trials and 12 were prospective cohort studies. We focussed on administration route, challenge agent and dose administered for data extraction. Overall, BCG studies including fluorescent BCG show the most immediate utility, and genetically modified Mycobacteria tuberculosis is the most tantalising prospect of discovery breakthrough. Conclusions: The TB-CHIM development group met in 2019 and 2022 to consider the results of the systematic review, to hear presentations from many of the senior authors whose work had been reviewed and to consider best ways forward. This paper reports both the systematic review and the deliberations. Registration: PROSPERO ( CRD42022302785; 21 January 2022).
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Affiliation(s)
- Stephen B. Gordon
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Simon Sichone
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Anthony E. Chirwa
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | | | | | - Daniela M. Ferreira
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
- Oxford Vaccine Group, University of Oxford, Oxford, UK
| | - JoAnne Flynn
- Centre for Vaccine Research, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Sarah Fortune
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, USA
| | | | | | - Helen McShane
- The Jenner Institute, University of Oxford, Oxford, UK
| | - Henry C Mwandumba
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Kondwani Jambo
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Keertan Dheda
- Faculty of Infectious and Tropical Diseases, Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
- Centre for Lung Infection and Immunity, Division of Pulmonology, Department of Medicine and UCT Lung Institute & South African MRC/UCT Centre for the Study of Antimicrobial Resistance, University of Cape Town, Cape Town, South Africa
| | | | | | - Naomi F Walker
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Ben Morton
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - TB Controlled Human Infection Model Development Group
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
- 1Day Africa, 1Day Sooner, Lusaka Province, Zambia
- Oxford Vaccine Group, University of Oxford, Oxford, UK
- Centre for Vaccine Research, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, USA
- Wellcome Trust, London, UK
- The Jenner Institute, University of Oxford, Oxford, UK
- Faculty of Infectious and Tropical Diseases, Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
- Centre for Lung Infection and Immunity, Division of Pulmonology, Department of Medicine and UCT Lung Institute & South African MRC/UCT Centre for the Study of Antimicrobial Resistance, University of Cape Town, Cape Town, South Africa
- Imperial College London, London, UK
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35
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McCann N, Emary K, Singh N, Mclean F, Camara S, Jones E, Kim YC, Liu X, Greenland M, Conlin K, Hill J, Verheul M, Robinson H, Angus B, Ramasamy MN, Levine MM, Pollard AJ. Accelerating clinical development of a live attenuated vaccine against Salmonella Paratyphi A (VASP): study protocol for an observer-participant-blind randomised control trial of a novel oral vaccine using a human challenge model of Salmonella Paratyphi A infection in healthy adult volunteers. BMJ Open 2023; 13:e068966. [PMID: 37225278 DOI: 10.1136/bmjopen-2022-068966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
INTRODUCTION This is the first efficacy study of an oral live attenuated vaccine against Salmonella Paratyphi A using a human challenge model of paratyphoid infection. S. Paratyphi A is responsible for 3.3 million cases of enteric fever every year, with over 19 000 deaths. Although improvements to sanitation and access to clean water are vital to reduce the burden of this condition, vaccination offers a cost-effective, medium-term solution. Efficacy trials of potential S. Paratyphi vaccine candidates in the field are unlikely to be feasible given the large number of participants required. Human challenge models therefore offer a unique, cost-effective solution to test efficacy of such vaccines. METHODS AND ANALYSIS This is an observer-blind, randomised, placebo-controlled trial phase I/II of the oral live-attenuated vaccine against S. Paratyphi A, CVD 1902. Volunteers will be randomised 1:1 to receive two doses of CVD 1902 or placebo, 14 days apart. One month following second vaccination all volunteers will ingest S. Paratyphi A bacteria with a bicarbonate buffer solution. They will be reviewed daily in the following 14 days and diagnosed with paratyphoid infection if the predefined microbiological or clinical diagnostic criteria are met. All participants will be treated with antibiotics on diagnosis, or at day 14 postchallenge if not diagnosed. The vaccine efficacy will be determined by comparing the relative attack rate, that is, the proportion of those diagnosed with paratyphoid infection, in the vaccine and placebo groups. ETHICS AND DISSEMINATION Ethical approval for this study has been obtained from the Berkshire Medical Research Ethics Committee (REC ref 21/SC/0330). The results will be disseminated via publication in a peer-reviewed journal and presentation at international conferences. TRIAL REGISTRATION NUMBER ISRCTN15485902.
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Affiliation(s)
- Naina McCann
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Katherine Emary
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Nisha Singh
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Florence Mclean
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Susana Camara
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Elizabeth Jones
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Young Chan Kim
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Xinxue Liu
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Melanie Greenland
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Kerry Conlin
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Jennifer Hill
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Marije Verheul
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Hannah Robinson
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Brian Angus
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Maheshi N Ramasamy
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Myron M Levine
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Andrew J Pollard
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
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36
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Singleton D, Ibarz-Pavon A, Swarthout TD, Bonomali F, Cornick J, Kalizang'oma A, Ntiza N, Brown C, Chipatala R, Nyangulu W, Chirombo J, Kawalazira G, Chibowa H, Mwansambo C, Maleta KM, French N, Heyderman RS. Cross-sectional health centre and community-based evaluation of the impact of pneumococcal and malaria vaccination on antibiotic prescription and usage, febrile illness and antimicrobial resistance in young children in Malawi: the IVAR study protocol. BMJ Open 2023; 13:e069560. [PMID: 37173105 DOI: 10.1136/bmjopen-2022-069560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/15/2023] Open
Abstract
INTRODUCTION Vaccination is a potentially critical component of efforts to arrest development and dissemination of antimicrobial resistance (AMR), though little is known about vaccination impact within low-income and middle-income countries. This study will evaluate the impact of vaccination on reducing carriage prevalence of resistant Streptococcus pneumoniae and extended spectrum beta-lactamase-producing Escherichia coli and Klebsiella species. We will leverage two large ongoing cluster-randomised vaccine evaluations in Malawi assessing; first, adding a booster dose to the 13-valent pneumococcal conjugate vaccine (PCV13) schedule, and second, introduction of the RTS,S/AS01 malaria vaccine. METHODS AND ANALYSIS Six cross-sectional surveys will be implemented within primary healthcare centres (n=3000 users of outpatient facilities per survey) and their local communities (n=700 healthy children per survey): three surveys in Blantyre district (PCV13 component) and three surveys in Mangochi district (RTS,S/AS01 component). We will evaluate antibiotic prescription practices and AMR carriage in children ≤3 years. For the PCV13 component, surveys will be conducted 9, 18 and 33 months following a 3+0 to 2+1 schedule change. For the RTS,S/AS01 component, surveys will be conducted 32, 44 and 56 months post-RTS,S/AS01 introduction. Six health centres in each study component will be randomly selected for study inclusion. Between intervention arms, the primary outcome will be the difference in penicillin non-susceptibility prevalence among S. pneumoniae nasopharyngeal carriage isolates in healthy children. The study is powered to detect an absolute change of 13 percentage points (ie, 35% vs 22% penicillin non-susceptibility). ETHICS AND DISSEMINATION This study has been approved by the Kamuzu University of Health Sciences (Ref: P01-21-3249), University College London (Ref: 18331/002) and University of Liverpool (Ref: 9908) Research Ethics Committees. Parental/caregiver verbal or written informed consent will be obtained prior to inclusion or recruitment in the health centre-based and community-based activities, respectively. Results will be disseminated via the Malawi Ministry of Health, WHO, peer-reviewed publications and conference presentations.
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Affiliation(s)
- David Singleton
- Department of Clinical Infection, Microbiology & Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Ana Ibarz-Pavon
- Department of Clinical Infection, Microbiology & Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Todd D Swarthout
- Julius Center for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, The Netherlands
- Research Department of Infection, Division of Infection and Immunity, UCL, London, UK
| | - Farouck Bonomali
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Jennifer Cornick
- Department of Clinical Infection, Microbiology & Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Akuzike Kalizang'oma
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
- Research Department of Infection, Division of Infection and Immunity, UCL, London, UK
| | - Noah Ntiza
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Comfort Brown
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Raphael Chipatala
- Department of Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Wongani Nyangulu
- Department of Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - James Chirombo
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Malawi
| | | | | | | | | | - Neil French
- Department of Clinical Infection, Microbiology & Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Robert S Heyderman
- Research Department of Infection, Division of Infection and Immunity, UCL, London, UK
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Aiemjoy K, Seidman JC, Charles RC, Andrews JR. Seroepidemiology for Enteric Fever: Emerging Approaches and Opportunities. Open Forum Infect Dis 2023; 10:S21-S25. [PMID: 37274530 PMCID: PMC10236506 DOI: 10.1093/ofid/ofad021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023] Open
Abstract
Safe and effective typhoid conjugate vaccines (TCVs) are available, but many countries lack the high-resolution data needed to prioritize TCV introduction to the highest-risk communities. Here we discuss seroepidemiology-an approach using antibody response data to characterize infection burden-as a potential tool to fill this data gap. Serologic tests for typhoid have existed for over a hundred years, but only recently were antigens identified that were sensitive and specific enough to use as epidemiologic markers. These antigens, coupled with new methodological developments, permit estimating seroincidence-the rate at which new infections occur in a population-from cross-sectional serosurveys. These new tools open up many possible applications for enteric fever seroepidemiology, including generating high-resolution surveillance data, monitoring vaccine impact, and integrating with other serosurveillance initiatives. Challenges remain, including distinguishing Salmonella Typhi from Salmonella Paratyphi infections and accounting for reinfections. Enteric fever seroepidemiology can be conducted at a fraction of the cost, time, and sample size of surveillance blood culture studies and may enable more efficient and scalable surveillance for this important infectious disease.
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Affiliation(s)
- Kristen Aiemjoy
- Correspondence: Kristen Aiemjoy, PhD, MSc, Department of Public Health Sciences, University of California, Davis School of Medicine, One Shields Ave, Medical Sciences 1C, Davis, CA 95616 (); Jason Andrews, MD, SM, DTM&H, Stanford University School of Medicine, 300 Pasteur Dr, Rm S101D, MC 5107, Stanford, CA 94305 ()
| | | | - Richelle C Charles
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Jason R Andrews
- Correspondence: Kristen Aiemjoy, PhD, MSc, Department of Public Health Sciences, University of California, Davis School of Medicine, One Shields Ave, Medical Sciences 1C, Davis, CA 95616 (); Jason Andrews, MD, SM, DTM&H, Stanford University School of Medicine, 300 Pasteur Dr, Rm S101D, MC 5107, Stanford, CA 94305 ()
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38
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Chen J, Long JE, Vannice K, Shewchuk T, Kumar S, Duncan Steele A, Zaidi AKM. Taking on Typhoid: Eliminating Typhoid Fever as a Global Health Problem. Open Forum Infect Dis 2023; 10:S74-S81. [PMID: 37274535 PMCID: PMC10236514 DOI: 10.1093/ofid/ofad055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023] Open
Abstract
Typhoid fever is a significant global health problem that impacts people living in areas without access to clean water and sanitation. However, collaborative international partnerships and new research have improved both knowledge of the burden in countries with endemic disease and the tools for improved surveillance, including environmental surveillance. Two typhoid conjugate vaccines (TCVs) have achieved World Health Organization prequalification, with several more in the development pipeline. Despite hurdles posed by the coronavirus disease 2019 pandemic, multiple TCV efficacy trials have been conducted in high-burden countries, and data indicate that TCVs provide a high degree of protection from typhoid fever, are safe to use in young children, provide lasting protection, and have the potential to combat typhoid antimicrobial resistance. Now is the time to double down on typhoid control and elimination by sustaining progress made through water, sanitation, and hygiene improvements and accelerating TCV introduction in high-burden locations.
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Affiliation(s)
- Jessie Chen
- Enteric and Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, Washington, USA
| | - Jessica E Long
- Correspondence: Jessica Long, PhD MPH, 500 5th Ave N, Seattle, WA 98109 ()
| | - Kirsten Vannice
- Enteric and Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, Washington, USA
| | - Tanya Shewchuk
- Enteric and Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, Washington, USA
| | - Supriya Kumar
- Enteric and Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, Washington, USA
| | - A Duncan Steele
- Enteric and Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, Washington, USA
| | - Anita K M Zaidi
- Enteric and Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, Washington, USA
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Russell AL, Hampton LM, Sinha A, Luquero FJ, Abdelwahab J. Progress in the Typhoid Conjugate Vaccine Program Rollout Supported by Gavi During the COVID-19 Pandemic and the Path Forward. Open Forum Infect Dis 2023; 10:S13-S16. [PMID: 37274531 PMCID: PMC10236508 DOI: 10.1093/ofid/ofad042] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023] Open
Abstract
Gavi supports countries to introduce typhoid conjugate vaccine (TCV) with catch-up campaigns. Available TCVs are highly efficacious, equity-focused, and critical to curbing the expansion of antimicrobial resistance. Four Gavi-supported countries have introduced TCVs since 2018. In the wake of the COVID-19 emergency, momentum is building to scale up TCV introduction worldwide, supported by global partners and Gavi's funding for improved typhoid diagnostics.
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Affiliation(s)
- Allyson L Russell
- Correspondence: Allyson L. Russell, MSPH, Vaccine Programs, Gavi, The Vaccine Alliance, Chemin du Pommier 40, 1218 Le Grand-Saconnex, Geneva, Switzerland (); or Francisco J. Luquero, MD, PhD, Vaccine Programs, Gavi, The Vaccine Alliance, Chemin du Pommier 40, 1218 Le Grand-Saconnex, Geneva, Switzerland ()
| | - Lee M Hampton
- Vaccine Programs, Gavi, The Vaccine Alliance, Geneva, Switzerland
| | - Antara Sinha
- Vaccine Programs, Gavi, The Vaccine Alliance, Geneva, Switzerland
| | - Francisco J Luquero
- Correspondence: Allyson L. Russell, MSPH, Vaccine Programs, Gavi, The Vaccine Alliance, Chemin du Pommier 40, 1218 Le Grand-Saconnex, Geneva, Switzerland (); or Francisco J. Luquero, MD, PhD, Vaccine Programs, Gavi, The Vaccine Alliance, Chemin du Pommier 40, 1218 Le Grand-Saconnex, Geneva, Switzerland ()
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MacLennan CA, Stanaway J, Grow S, Vannice K, Steele AD. Salmonella Combination Vaccines: Moving Beyond Typhoid. Open Forum Infect Dis 2023; 10:S58-S66. [PMID: 37274529 PMCID: PMC10236507 DOI: 10.1093/ofid/ofad041] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023] Open
Abstract
There is now a robust pipeline of licensed and World Health Organization (WHO)-prequalified typhoid conjugate vaccines with a steady progression of national introductions. However, typhoid fever is responsible for less than half the total global burden of Salmonella disease, and even less among children aged <5 years. Invasive nontyphoidal Salmonella disease is the dominant clinical presentation of Salmonella in Africa, and over a quarter of enteric fever in Asia is due to paratyphoid A. In this article, we explore the case for combination Salmonella vaccines, review the current pipeline of these vaccines, and discuss key considerations for their development, including geographies of use, age of administration, and pathways to licensure. While a trivalent typhoid/nontyphoidal Salmonella vaccine is attractive for Africa, and a bivalent enteric fever vaccine for Asia, a quadrivalent vaccine covering the 4 main disease-causing serovars of Salmonella enterica would provide a single vaccine option for global Salmonella coverage.
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Affiliation(s)
- Calman A MacLennan
- Enteric and Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, Washington, USA
- Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Jeffrey Stanaway
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, Washington, USA
| | - Stephanie Grow
- Enteric and Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, Washington, USA
| | - Kirsten Vannice
- Enteric and Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, Washington, USA
| | - A Duncan Steele
- Enteric and Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, Washington, USA
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Nampota-Nkomba N, Carey ME, Jamka LP, Fecteau N, Neuzil KM. Using Typhoid Conjugate Vaccines to Prevent Disease, Promote Health Equity, and Counter Drug-Resistant Typhoid Fever. Open Forum Infect Dis 2023; 10:S6-S12. [PMID: 37274532 PMCID: PMC10236511 DOI: 10.1093/ofid/ofad022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023] Open
Abstract
Typhoid fever is a serious disease that disproportionately impacts children in low-resource settings in sub-Saharan Africa, South and Southeast Asia, and the Western Pacific. The prevalence of antimicrobial-resistant strains of S. Typhi continue to increase worldwide. Two safe, effective, and cost-effective typhoid conjugate vaccines (TCVs) are World Health Organization-prequalified for the prevention of typhoid fever in children as young as 6 months. Typhoid conjugate vaccines have proven effectiveness in preventing drug-resistant S. Typhi and have been deployed successfully in outbreak response and routine immunization scenarios. Broad and equitable distribution of TCVs is essential to combat the spread and potentially devastating consequences of typhoid fever. It is vital to empower decision-makers in typhoid-endemic countries to introduce TCVs and for leaders to embrace this critical tool to prevent typhoid fever, slow the spread of drug-resistant S. Typhi strains, promote health equity, and save lives.
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Affiliation(s)
| | - Megan E Carey
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Department of Medicine, University of Cambridge, Cambridge, UK
| | - Leslie P Jamka
- Correspondence: Leslie Jamka, MEM, MS, 685 W. Baltimore Street, #480, Baltimore, MD 21201, USA (). Kathleen Neuzil, 685 W. Baltimore Street, #480 Baltimore, MD 21201, USA ()
| | - Natalie Fecteau
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kathleen M Neuzil
- Correspondence: Leslie Jamka, MEM, MS, 685 W. Baltimore Street, #480, Baltimore, MD 21201, USA (). Kathleen Neuzil, 685 W. Baltimore Street, #480 Baltimore, MD 21201, USA ()
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Neuzil KM. Enteric Fever - Tools for Prevention. N Engl J Med 2023; 388:1526-1528. [PMID: 37075145 DOI: 10.1056/nejme2300753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
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Khanam F, Babu G, Rahman N, Liu X, Rajib NH, Ahmed SU, Hossen MI, Biswas PK, Kelly S, Thesis-Nyland K, Mujadidi Y, McMillan NAJ, Pollard AJ, Clemens JD, Qadri F. Immune responses in children after vaccination with a typhoid Vi-tetanus toxoid conjugate vaccine in Bangladesh. Vaccine 2023; 41:3137-3140. [PMID: 37061369 DOI: 10.1016/j.vaccine.2023.04.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/15/2022] [Accepted: 04/04/2023] [Indexed: 04/17/2023]
Abstract
A cluster-randomized trial of Vi-TT was conducted in Dhaka, Bangladesh, using JE vaccine as the control. A subset of 1,500 children were randomly selected on 2:1 basis (Vi-TT vs JE) to assess immune response. Blood was collected before vaccination, and on days 28, 545 and 730 post-vaccination and plasma anti-Vi-IgG response was measured. A robust, persistent antibody response was induced after single dose of Vi-TT, even after 2 years of vaccination. While there is no accepted serological antibody threshold of protection, analyzing the antibodies of children who received Vi-TT provides evidence that may later be useful in predicting population protection.
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Affiliation(s)
- Farhana Khanam
- International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh; Menzies Health Institute Queensland and School of Pharmacy and Medical Science, Griffith University, Gold Coast, Australia
| | - Golap Babu
- International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Nazia Rahman
- International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Xinxue Liu
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Nazmul Hasan Rajib
- International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Shams Uddin Ahmed
- International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Md Ismail Hossen
- International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | | | - Sarah Kelly
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Katherine Thesis-Nyland
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Yama Mujadidi
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Nigel A J McMillan
- Menzies Health Institute Queensland and School of Pharmacy and Medical Science, Griffith University, Gold Coast, Australia
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - John D Clemens
- International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh; International Vaccine Institute, Seoul, Republic of Korea; UCLA Fielding, School of Public Health, Los Angeles, CA 90095-1772, USA
| | - Firdausi Qadri
- International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
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Khanam F, Kim DR, Liu X, Voysey M, Pitzer VE, Zaman K, Pollard AJ, Qadri F, Clemens JD. Assessment of vaccine herd protection in a cluster-randomised trial of Vi conjugate vaccine against typhoid fever: results of further analysis. EClinicalMedicine 2023; 58:101925. [PMID: 37090439 PMCID: PMC10114505 DOI: 10.1016/j.eclinm.2023.101925] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 03/07/2023] [Accepted: 03/09/2023] [Indexed: 04/25/2023] Open
Abstract
Background A cluster-randomised trial of Vi-tetanus toxoid (Vi-TT) conjugate vaccine conducted in urban Bangladeshi children found a high level of direct protection by Vi-TT but no significant vaccine herd protection. We reassessed the trial using a "fried egg" analysis to evaluate whether herd protection might have been obscured by transmission of typhoid into the clusters from the outside. Methods A participant- and observer-blind, cluster-randomised trial was conducted between February 14, 2018 and August 12, 2019 in three wards of Mirpur, a densely populated urban area of Dhaka, Bangladesh. Children 9 months to under 16 years of age in 150 geographic clusters, which had a total of 311,289 persons present at baseline or entering during follow-up, were randomised by cluster to a single-dose of Vi-TT or Japanese encephalitis (JE) vaccine. Vi-TT protection against typhoid fever, detected at 8 treatment centres serving the study population, was compared in the original clusters for the trial, and for progressively more central subclusters ("yolks" of the "fried egg") of the cluster residents. If transmission of typhoid into the clusters had diluted observed vaccine herd protection, we hypothesised that analysis of the innermost "yolks" would reveal vaccine herd protection that was not evident in analysis of the entire clusters. The trial is registered at www.isrctn.com as ISRCTN11643110. Findings At ≤18 months of follow-up, total vaccine effectiveness (protection of Vi-TT recipients relative to JE vaccine recipients) was 85% (95% CI: 76%, 90%); indirect effectiveness (protection of non-Vi-TT recipients in Vi-TT clusters relative to non-JE vaccine recipients in JE vaccine clusters) was 17% (95% CI: -13%, 40%); and overall effectiveness (protection of all residents in the Vi-TT clusters relative to all residents of the JE vaccine clusters) was 57% (95% CI: 44%, 66%). Analyses of subpopulations in inner 75%, 50% and 25% "yolks" of the clusters failed to reveal significant changes in any of these estimates. Interpretation Our analysis did not reveal Vi-TT herd protection in the trial. Consideration should be given to exploring whether targeting adults as well as children with Vi-TT yields appreciable levels of vaccine herd protection. Funding Bill & Melinda Gates Foundation (OPP1151153, INV-025388).
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Affiliation(s)
- Farhana Khanam
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
- Corresponding author. Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
| | | | - Xinxue Liu
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Merryn Voysey
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Virginia E. Pitzer
- Department of Epidemiology of Microbial Disease and Public Health Modeling Unit, Yale School of Public Health, Yale University, New Haven, CT, USA
| | - K. Zaman
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Andrew J. Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Firdausi Qadri
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - John D. Clemens
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
- International Vaccine Institute, Seoul, South Korea
- Department of Epidemiology, UCLA Fielding School of Public Health, Los Angeles, CA, USA
- Center for Vaccine Innovation, Korea University, Seoul, South Korea
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Jossi SE, Arcuri M, Alshayea A, Persaud RR, Marcial-Juárez E, Palmieri E, Di Benedetto R, Pérez-Toledo M, Pillaye J, Channell WM, Schager AE, Lamerton RE, Cook CN, Goodall M, Haneda T, Bäumler AJ, Jackson-Jones LH, Toellner KM, MacLennan CA, Henderson IR, Micoli F, Cunningham AF. Vi polysaccharide and conjugated vaccines afford similar early, IgM or IgG-independent control of infection but boosting with conjugated Vi vaccines sustains the efficacy of immune responses. Front Immunol 2023; 14:1139329. [PMID: 37033932 PMCID: PMC10076549 DOI: 10.3389/fimmu.2023.1139329] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 03/13/2023] [Indexed: 04/11/2023] Open
Abstract
Introduction Vaccination with Vi capsular polysaccharide (Vi-PS) or protein-Vi typhoid conjugate vaccine (TCV) can protect adults against Salmonella Typhi infections. TCVs offer better protection than Vi-PS in infants and may offer better protection in adults. Potential reasons for why TCV may be superior in adults are not fully understood. Methods and results Here, we immunized wild-type (WT) mice and mice deficient in IgG or IgM with Vi-PS or TCVs (Vi conjugated to tetanus toxoid or CRM197) for up to seven months, with and without subsequent challenge with Vi-expressing Salmonella Typhimurium. Unexpectedly, IgM or IgG alone were similarly able to reduce bacterial burdens in tissues, and this was observed in response to conjugated or unconjugated Vi vaccines and was independent of antibody being of high affinity. Only in the longer-term after immunization (>5 months) were differences observed in tissue bacterial burdens of mice immunized with Vi-PS or TCV. These differences related to the maintenance of antibody responses at higher levels in mice boosted with TCV, with the rate of fall in IgG titres induced to Vi-PS being greater than for TCV. Discussion Therefore, Vi-specific IgM or IgG are independently capable of protecting from infection and any superior protection from vaccination with TCV in adults may relate to responses being able to persist better rather than from differences in the antibody isotypes induced. These findings suggest that enhancing our understanding of how responses to vaccines are maintained may inform on how to maximize protection afforded by conjugate vaccines against encapsulated pathogens such as S. Typhi.
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Affiliation(s)
- Siân E. Jossi
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Melissa Arcuri
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
- GSK Vaccines Institute for Global Health SRL, Siena, Italy
| | - Areej Alshayea
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Ruby R. Persaud
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Edith Marcial-Juárez
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Elena Palmieri
- GSK Vaccines Institute for Global Health SRL, Siena, Italy
| | | | - Marisol Pérez-Toledo
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Jamie Pillaye
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Will M. Channell
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Anna E. Schager
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Rachel E. Lamerton
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Charlotte N. Cook
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Margaret Goodall
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Takeshi Haneda
- Laboratory of Microbiology, School of Pharmacy, Kitasato University, Tokyo, Japan
| | - Andreas J. Bäumler
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, CA, United States
| | - Lucy H. Jackson-Jones
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster, United Kingdom
| | - Kai-Michael Toellner
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Calman A. MacLennan
- Bill & Melinda Gates Foundation, London, United Kingdom
- Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Ian R. Henderson
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD, Australia
| | | | - Adam F. Cunningham
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
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Phillips MT, Antillon M, Bilcke J, Bar-Zeev N, Limani F, Debellut F, Pecenka C, Neuzil KM, Gordon MA, Thindwa D, Paltiel AD, Yaesoubi R, Pitzer VE. Cost-effectiveness analysis of typhoid conjugate vaccines in an outbreak setting: a modeling study. BMC Infect Dis 2023; 23:143. [PMID: 36890448 PMCID: PMC9993384 DOI: 10.1186/s12879-023-08105-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 02/20/2023] [Indexed: 03/10/2023] Open
Abstract
BACKGROUND Several prolonged typhoid fever epidemics have been reported since 2010 throughout eastern and southern Africa, including Malawi, caused by multidrug-resistant Salmonella Typhi. The World Health Organization recommends the use of typhoid conjugate vaccines (TCVs) in outbreak settings; however, current data are limited on how and when TCVs might be introduced in response to outbreaks. METHODOLOGY We developed a stochastic model of typhoid transmission fitted to data from Queen Elizabeth Central Hospital in Blantyre, Malawi from January 1996 to February 2015. We used the model to evaluate the cost-effectiveness of vaccination strategies over a 10-year time horizon in three scenarios: (1) when an outbreak is likely to occur; (2) when an outbreak is unlikely to occur within the next ten years; and (3) when an outbreak has already occurred and is unlikely to occur again. We considered three vaccination strategies compared to the status quo of no vaccination: (a) preventative routine vaccination at 9 months of age; (b) preventative routine vaccination plus a catch-up campaign to 15 years of age; and (c) reactive vaccination with a catch-up campaign to age 15 (for Scenario 1). We also explored variations in outbreak definitions, delays in implementation of reactive vaccination, and the timing of preventive vaccination relative to the outbreak. RESULTS Assuming an outbreak occurs within 10 years, we estimated that the various vaccination strategies would prevent a median of 15-60% of disability-adjusted life-years (DALYs). Reactive vaccination was the preferred strategy for WTP values of $0-300 per DALY averted. For WTP values > $300, introduction of preventative routine TCV immunization with a catch-up campaign was the preferred strategy. Routine vaccination with a catch-up campaign was cost-effective for WTP values above $890 per DALY averted if no outbreak occurs and > $140 per DALY averted if implemented after the outbreak has already occurred. CONCLUSIONS Countries for which the spread of antimicrobial resistance is likely to lead to outbreaks of typhoid fever should consider TCV introduction. Reactive vaccination can be a cost-effective strategy, but only if delays in vaccine deployment are minimal; otherwise, introduction of preventive routine immunization with a catch-up campaign is the preferred strategy.
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Affiliation(s)
- Maile T Phillips
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, 60 College St., P.O. Box 208034, New Haven, CT, 06520-8034, USA
| | - Marina Antillon
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Joke Bilcke
- Center for Health Economics Research and Modeling Infectious Diseases, University of Antwerp, Antwerp, Belgium
| | - Naor Bar-Zeev
- International Vaccine Access Center, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Malawi Liverpool Wellcome Programme, Blantyre, Malawi
| | - Fumbani Limani
- Malawi Liverpool Wellcome Programme, Blantyre, Malawi.,Kamuzu University of Health Sciences, Blantyre, Malawi
| | | | - Clint Pecenka
- Center for Vaccine Innovation and Access, PATH, Seattle, WA, USA
| | - Kathleen M Neuzil
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Melita A Gordon
- Malawi Liverpool Wellcome Programme, Blantyre, Malawi.,Kamuzu University of Health Sciences, Blantyre, Malawi.,Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Deus Thindwa
- Malawi Liverpool Wellcome Programme, Blantyre, Malawi.,Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - A David Paltiel
- Department of Health Policy, Yale School of Public Health, New Haven, CT, USA
| | - Reza Yaesoubi
- Department of Health Policy, Yale School of Public Health, New Haven, CT, USA
| | - Virginia E Pitzer
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, 60 College St., P.O. Box 208034, New Haven, CT, 06520-8034, USA.
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Ok Baik Y, Lee Y, Lee C, Kyung Kim S, Park J, Sun M, Jung D, Young Jang J, Jun Yong T, Woo Park J, Jeong S, Lim S, Hyun Han S, Keun Choi S. A Phase II/III, Multicenter, Observer-blinded, Randomized, Non-inferiority and Safety, study of typhoid conjugate vaccine (EuTCV) compared to Typbar-TCV® in healthy 6 Months-45 years aged participants. Vaccine 2023; 41:1753-1759. [PMID: 36774331 DOI: 10.1016/j.vaccine.2022.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/23/2022] [Accepted: 12/01/2022] [Indexed: 02/11/2023]
Abstract
The typhoid conjugate vaccine (TCV) ensures a long-lasting protective immune response, requires fewer doses and is fit for children under 2 years of age. From Phase I study, EuTCV displayed considerable immunogenicity and reliable safety, thus endorsing further examination in Phase II/III trials. Therefore, a clinical Phase II/III study (NCT04830371) was conducted to evaluate its efficacy in healthy Filipino participants aged 6 months to 45 years through administration of the test vaccine (Arm A, B, and C) or comparator vaccine Typbar-TCV® (Arm D). Sera samples were collected pre-vaccination (Visit 1) and post-vaccination (Visit 4, Day 28) to assess the immunogenicity of EuTCV and Typbar-TCV®. During the study, participants were regularly monitored through scheduled visits to the clinic to report any adverse events associated with the vaccine. For vaccine safety, the proportion of solicited and unsolicited Treatment-Emergent Adverse Events was all comparable between EuTCV and Typbar-TCV® groups. A single dose of EuTCV produced seroconversion in 99.4% of treated participants, with seroconversion rates non-inferior to that of Typbar-TCV®. Batch-to-batch consistency was concluded based on the 90% Confidence Interval of the geometric mean ratio (EuTCV Arm A, B, and C) at Week 4, lying within the equivalence margin of 0.5 to 2.0 for all batches. Results from this Phase II/III clinical trial of EuTCV in healthy volunteers show comparable safety and considerable immunogenicity, compared to Typbar-TCV®, meeting the objectives of this pivotal study. ClinicalTrials.gov registration number: NCT04830371.
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Affiliation(s)
| | | | - Chankyu Lee
- R&D Center, EuBiologics Co., Ltd., Chuncheon, Republic of Korea
| | - Soo Kyung Kim
- R&D Center, EuBiologics Co., Ltd., Chuncheon, Republic of Korea
| | | | - Meixiang Sun
- R&D Center, EuBiologics Co., Ltd., Chuncheon, Republic of Korea
| | - DaYe Jung
- EuBiologics Co., Ltd., Seoul, Republic of Korea
| | - Jin Young Jang
- R&D Center, EuBiologics Co., Ltd., Chuncheon, Republic of Korea
| | - Tae Jun Yong
- R&D Center, EuBiologics Co., Ltd., Chuncheon, Republic of Korea
| | - Jeong Woo Park
- Department of Oral Microbiology and Immunology, and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Sungho Jeong
- Department of Oral Microbiology and Immunology, and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Suwon Lim
- Department of Oral Microbiology and Immunology, and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Seung Hyun Han
- Department of Oral Microbiology and Immunology, and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
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Hoffman SA, Sikorski MJ, Levine MM. Chronic Salmonella Typhi carriage at sites other than the gallbladder. PLoS Negl Trop Dis 2023; 17:e0011168. [PMID: 36952437 PMCID: PMC10035749 DOI: 10.1371/journal.pntd.0011168] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023] Open
Abstract
Typhoid fever caused by infection with Salmonella enterica subspecies enterica serotype Typhi (S. Typhi), an important public health problem in many low- and middle-income countries, is transmitted by ingestion of water or food contaminated by feces or urine from individuals with acute or chronic S. Typhi infection. Most chronic S. Typhi carriers (shedding for ≥12 months) harbor infection in their gallbladder wherein preexisting pathologies, particularly cholelithiasis, provide an environment that fosters persistence. Much less appreciated is the existence of non-gallbladder hepatobiliary chronic S. Typhi carriers and urinary carriers. The former includes parasitic liver flukes as a chronic carriage risk factor. Chronic urinary carriers typically have pathology of their urinary tract, with or without renal or bladder stones. Even as the prevalence of multidrug-resistant and extensively drug-resistant S. Typhi strains is rising, global implementation of highly effective typhoid vaccines is increasing. There is also renewed interest in identifying, monitoring, and (where possible) treating chronic carriers who comprise the long-term reservoir of S. Typhi.
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Affiliation(s)
- Seth A Hoffman
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Michael J Sikorski
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Myron M Levine
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
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49
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Gordon SB, Sichone S, Chirwa AE, Hazenberg P, Kafuko Z, Ferreira DM, Flynn J, Fortune S, Balasingam S, Biagini GA, McShane H, Mwandumba HC, Jambo K, Dheda K, Raj Sharma N, Robertson BD, Walker NF, Morton B. Practical considerations for a TB controlled human infection model (TB-CHIM); the case for TB-CHIM in Africa, a systematic review of the literature and report of 2 workshop discussions in UK and Malawi. Wellcome Open Res 2023; 8:71. [PMID: 37007907 PMCID: PMC10064019 DOI: 10.12688/wellcomeopenres.18767.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/26/2023] [Indexed: 02/12/2023] Open
Abstract
Background: Tuberculosis (TB) remains a major challenge in many domains including diagnosis, pathogenesis, prevention, treatment, drug resistance and long-term protection of the public health by vaccination. A controlled human infection model (CHIM) could potentially facilitate breakthroughs in each of these domains but has so far been considered impossible owing to technical and safety concerns. Methods: A systematic review of mycobacterial human challenge studies was carried out to evaluate progress to date, best possible ways forward and challenges to be overcome. We searched MEDLINE (1946 to current) and CINAHL (1984 to current) databases; and Google Scholar to search citations in selected manuscripts. The final search was conducted 3 rd February 2022. Inclusion criteria: adults ≥18 years old; administration of live mycobacteria; and interventional trials or cohort studies with immune and/or microbiological endpoints. Exclusion criteria: animal studies; studies with no primary data; no administration of live mycobacteria; retrospective cohort studies; case-series; and case-reports. Relevant tools (Cochrane Collaboration for RCTs and Newcastle-Ottawa Scale for non-randomised studies) were used to assess risk of bias and present a narrative synthesis of our findings. Results: The search identified 1,388 titles for review; of these 90 were reviewed for inclusion; and 27 were included. Of these, 15 were randomised controlled trials and 12 were prospective cohort studies. We focussed on administration route, challenge agent and dose administered for data extraction. Overall, BCG studies including fluorescent BCG show the most immediate utility, and genetically modified Mycobacteria tuberculosis is the most tantalising prospect of discovery breakthrough. Conclusions: The TB-CHIM development group met in 2019 and 2022 to consider the results of the systematic review, to hear presentations from many of the senior authors whose work had been reviewed and to consider best ways forward. This paper reports both the systematic review and the deliberations. Registration: PROSPERO ( CRD42022302785; 21 January 2022).
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Affiliation(s)
- Stephen B. Gordon
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Simon Sichone
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Anthony E. Chirwa
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | | | | | - Daniela M. Ferreira
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
- Oxford Vaccine Group, University of Oxford, Oxford, UK
| | - JoAnne Flynn
- Centre for Vaccine Research, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Sarah Fortune
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, USA
| | | | | | - Helen McShane
- The Jenner Institute, University of Oxford, Oxford, UK
| | - Henry C Mwandumba
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Kondwani Jambo
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Keertan Dheda
- Faculty of Infectious and Tropical Diseases, Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
- Centre for Lung Infection and Immunity, Division of Pulmonology, Department of Medicine and UCT Lung Institute & South African MRC/UCT Centre for the Study of Antimicrobial Resistance, University of Cape Town, Cape Town, South Africa
| | | | | | - Naomi F Walker
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Ben Morton
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - TB Controlled Human Infection Model Development Group
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
- 1Day Africa, 1Day Sooner, Lusaka Province, Zambia
- Oxford Vaccine Group, University of Oxford, Oxford, UK
- Centre for Vaccine Research, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Harvard T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts, USA
- Wellcome Trust, London, UK
- The Jenner Institute, University of Oxford, Oxford, UK
- Faculty of Infectious and Tropical Diseases, Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
- Centre for Lung Infection and Immunity, Division of Pulmonology, Department of Medicine and UCT Lung Institute & South African MRC/UCT Centre for the Study of Antimicrobial Resistance, University of Cape Town, Cape Town, South Africa
- Imperial College London, London, UK
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50
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Burrows H, Antillón M, Gauld JS, Kim JH, Mogasale V, Ryckman T, Andrews JR, Lo NC, Pitzer VE. Comparison of model predictions of typhoid conjugate vaccine public health impact and cost-effectiveness. Vaccine 2023; 41:965-975. [PMID: 36586741 PMCID: PMC9880559 DOI: 10.1016/j.vaccine.2022.12.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/31/2022]
Abstract
Models are useful to inform policy decisions on typhoid conjugate vaccine (TCV) deployment in endemic settings. However, methodological choices can influence model-predicted outcomes. To provide robust estimates for the potential public health impact of TCVs that account for structural model differences, we compared four dynamic and one static mathematical model of typhoid transmission and vaccine impact. All models were fitted to a common dataset of age-specific typhoid fever cases in Kolkata, India. We evaluated three TCV strategies: no vaccination, routine vaccination at 9 months of age, and routine vaccination at 9 months with a one-time catch-up campaign (ages 9 months to 15 years). The primary outcome was the predicted percent reduction in symptomatic typhoid cases over 10 years after vaccine introduction. For three models with economic analyses (Models A-C), we also compared the incremental cost-effectiveness ratios (ICERs), calculated as the incremental cost (US$) per disability-adjusted life-year (DALY) averted. Routine vaccination was predicted to reduce symptomatic cases by 10-46 % over a 10-year time horizon under an optimistic scenario (95 % initial vaccine efficacy and 19-year mean duration of protection), and by 2-16 % under a pessimistic scenario (82 % initial efficacy and 6-year mean protection). Adding a catch-up campaign predicted a reduction in incidence of 36-90 % and 6-35 % in the optimistic and pessimistic scenarios, respectively. Vaccine impact was predicted to decrease as the relative contribution of chronic carriers to transmission increased. Models A-C all predicted routine vaccination with or without a catch-up campaign to be cost-effective compared to no vaccination, with ICERs varying from $95-789 per DALY averted; two models predicted the ICER of routine vaccination alone to be greater than with the addition of catch-up campaign. Despite differences in model-predicted vaccine impact and cost-effectiveness, routine vaccination plus a catch-up campaign is likely to be impactful and cost-effective in high incidence settings such as Kolkata.
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Affiliation(s)
- Holly Burrows
- Yale School of Public Health, Yale University, New Haven, CT, USA.
| | - Marina Antillón
- Yale School of Public Health, Yale University, New Haven, CT, USA; Swiss Tropical and Public Health Institute, Allschwil, Switzerland; University of Basel, Basel, Switzerland
| | - Jillian S Gauld
- Institute for Disease Modeling, Bill & Melinda Gates Foundation, Seattle, WA, USA
| | - Jong-Hoon Kim
- Public Health, Access, and Vaccine Epidemiology (PAVE) Unit, International Vaccine Institute, Seoul, Republic of Korea
| | - Vittal Mogasale
- Policy and Economic Research Department, International Vaccine Institute, Seoul 08826, Republic of Korea
| | - Theresa Ryckman
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Jason R Andrews
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Nathan C Lo
- Division of HIV, Infectious Diseases, and Global Medicine, University of California, San Francisco, San Francisco, CA, USA
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