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Jaishwal P, Jha K, Singh SP. Revisiting the dimensions of universal vaccine with special focus on COVID-19: Efficacy versus methods of designing. Int J Biol Macromol 2024; 277:134012. [PMID: 39048013 DOI: 10.1016/j.ijbiomac.2024.134012] [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: 10/28/2023] [Revised: 05/28/2024] [Accepted: 07/17/2024] [Indexed: 07/27/2024]
Abstract
Even though the use of SARS-CoV-2 vaccines during the COVID-19 pandemic showed unprecedented success in a short time, it also exposed a flaw in the current vaccine design strategy to offer broad protection against emerging variants of concern. However, developing broad-spectrum vaccines is still a challenge for immunologists. The development of universal vaccines against emerging pathogens and their variants appears to be a practical solution to mitigate the economic and physical effects of the pandemic on society. Very few reports are available to explain the basic concept of universal vaccine design and development. This review provides an overview of the innate and adaptive immune responses generated against vaccination and essential insight into immune mechanisms helpful in designing universal vaccines targeting influenza viruses and coronaviruses. In addition, the characteristics, safety, and factors affecting the efficacy of universal vaccines have been discussed. Furthermore, several advancements in methods worthy of designing universal vaccines are described, including chimeric immunogens, heterologous prime-boost vaccines, reverse vaccinology, structure-based antigen design, pan-reactive antibody vaccines, conserved neutralizing epitope-based vaccines, mosaic nanoparticle-based vaccines, etc. In addition to the several advantages, significant potential constraints, such as defocusing the immune response and subdominance, are also discussed.
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Affiliation(s)
- Puja Jaishwal
- Department of Biotechnology, Mahatma Gandhi Central University, Motihari, India
| | - Kisalay Jha
- Department of Biotechnology, Mahatma Gandhi Central University, Motihari, India
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2
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Binik A. Should Children Be Included in Human Challenge Studies? Ethics Hum Res 2024; 46:2-15. [PMID: 38629235 DOI: 10.1002/eahr.500208] [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] [Indexed: 04/19/2024]
Abstract
Human challenge studies, in which human research subjects are intentionally exposed to pathogens to contribute to scientific knowledge, raise many ethical complexities. One controversial question is whether it is ethically permissible to include children as participants. Commentary of the past decades endorses the exclusion of children, while new guidance suggests that pediatric human challenge studies can be ethically permissible. This paper argues that neither children's exclusion nor their inclusion are well justified. I examine and reject three arguments for exclusion, but suggest that these arguments establish pediatric human challenge studies as a complex ethical category of research that requires caution. I then argue for a strong presumption against children's inclusion, by drawing on an analogy to children's inclusion in phase I trials, emphasizing a requirement of necessity, and suggesting that accommodating children's vulnerability promotes an age de-escalation approach for pediatric human challenge studies research. In the final section, I suggest a procedure for ethics review.
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Affiliation(s)
- Ariella Binik
- Associate professor of philosophy at McMaster University
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3
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ElSherif M, Halperin SA. Benefits of Combining Molecular Biology and Controlled Human Infection Model Methodologies in Advancing Vaccine Development. J Mol Biol 2023; 435:168322. [PMID: 37866477 DOI: 10.1016/j.jmb.2023.168322] [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: 01/31/2023] [Revised: 10/13/2023] [Accepted: 10/17/2023] [Indexed: 10/24/2023]
Abstract
Infectious diseases continue to account for a significant portion of global deaths despite the use of vaccines for several centuries. Immunization programs around the world are a testament to the great success of multiple vaccines, yet there are still diseases without vaccines and others that require safer more effective ones. Addressing uncontrolled and emerging disease threats is restrained by the limitations and bottlenecks encountered with traditional vaccine development paradigms. Recent advances in modern molecular biology technologies have enhanced the interrogation of host pathogen interaction and deciphered complex pathways, thereby uncovering the myriad interplay of biological events that generate immune protection against foreign agents. Consequent to insights into the immune system, modern biology has been instrumental in the development and production of next generation 21st century vaccines. As these biological tools, commonly and collectively referred to as 'omics, became readily available, there has been a renewed consideration of Controlled Human Infection Models (CHIMs). Successful and reproducible CHIMs can complement modern molecular biology for the study of infectious diseases and development of effective vaccines in a regulated process that mitigates risk, cost, and time, with capacity to discern immune correlates of protection.
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Affiliation(s)
- May ElSherif
- Canadian Center for Vaccinology, IWK Health, Nova Scotia Health, and Dalhousie University, Halifax, Nova Scotia, Canada.
| | - Scott A Halperin
- Canadian Center for Vaccinology, IWK Health, Nova Scotia Health, and Dalhousie University, Halifax, Nova Scotia, Canada.
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4
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Katzer M, Salloch S, Schindler C, Mertz M. Ethical Requirements for Human Challenge Studies: A Systematic Review of Reasons. Clin Pharmacol Ther 2023; 114:1209-1219. [PMID: 37716911 DOI: 10.1002/cpt.3054] [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: 07/17/2023] [Accepted: 09/11/2023] [Indexed: 09/18/2023]
Abstract
Human challenge studies (HCS) are controlled clinical trials in which participants are deliberately infected with a pathogen. Such trials are being developed for an increasing number of diseases. Partly as a result of the coronavirus disease 2019 (COVID-19) pandemic, there has been a recent ethical debate about the reasons for and against HCS in general, or rather, about the requirements that individual HCS must fulfill to be ethically acceptable. A systematic review was conducted to categorize and summarize such requirements and the reasons given for them. Ethics literature was searched in PubMed, Google Scholar, BELIT, and PhilPapers; eligibility criteria were articles published in a scientific/scholarly journal (original research, reviews, editorials, opinion pieces, and conference/meeting reports). Of 1,322 records identified, 161 publications were included, with 183 requirements (with associated reasons) in 10 thematic categories extracted via qualitative content analysis. In synthesizing and interpreting the requirements and their reasons, three issues emerge as particularly sensitive in the case of HCS: the meaning of the right to withdraw from research procedures, communication of researchers with the public and various stakeholders, and the conditions of informed consent. However, four other issues, not specific to HCS, stand out as the most controversial: the acceptable level of risk to participants, payment of participants, protection of vulnerable groups, and standards for international collaborations. Controversies in these areas indicate that further debate is warranted, possibly leading to more specific instructions in ethics guidance documents.
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Affiliation(s)
- Matthias Katzer
- Institute for Ethics, History, and Philosophy of Medicine, Hannover Medical School (MHH), Hannover, Germany
| | - Sabine Salloch
- Institute for Ethics, History, and Philosophy of Medicine, Hannover Medical School (MHH), Hannover, Germany
| | - Christoph Schindler
- Center for Clinical Trials (ZKS), Early Clinical Trial Unit (ECTU) & Center for Pharmacology and Toxicology, Hannover Medical School (MHH), Hannover, Germany
| | - Marcel Mertz
- Institute for Ethics, History, and Philosophy of Medicine, Hannover Medical School (MHH), Hannover, Germany
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5
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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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6
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Enkel SL, Hla TK, Wong B, Pickering J, Barnett TC, Thomas HMM, Lansbury N, Carapetis JR, Manning L, Bowen AC. Searching for Strep A in the clinical environment during a human challenge trial: a sub-study protocol. Access Microbiol 2023; 5:000650.v3. [PMID: 37841095 PMCID: PMC10569665 DOI: 10.1099/acmi.0.000650.v3] [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] [Received: 06/13/2023] [Accepted: 09/05/2023] [Indexed: 10/17/2023] Open
Abstract
Streptococcus pyogenes (also known as group A Streptococcus , Strep A) is an obligate human pathogen with significant global morbidity and mortality. Transmission is believed to occur primarily between individuals via respiratory droplets, but knowledge about other potential sources of transmission via aerosols or the environment is limited. Such knowledge is required to design optimal interventions to control transmission, particularly in endemic settings. We aim to detail an experimental methodology to assess the transmission potential of Strep A in a clinical environment. We will examine potential sources of transmission in up to 20 participants recruited to the Controlled human infection for penicillin against Streptococcus pyogenes (CHIPS) Trial. Three approaches to understanding transmission will be used: the use of selective agar settle plates to capture possible droplet or airborne spread of Strep A; measurement of the possible distance of Strep A droplet spread during conversation; and environmental swabbing of personal and common high-touch items to detect the presence of Strep A on hard and soft surfaces. All methods are designed to allow for an assessment of transmission potential by symptomatic, asymptomatic and non-cases. Ethical approval has been obtained through Bellberry Human Research Ethics Committee (approval 2021-03-295). Trial registration number: ACTRN12621000751875. Any results elicited from these experiments will be of benefit to the scientific literature in improving our knowledge of opportunities to prevent Strep A transmission as a direct component of the primordial prevention of rheumatic fever. Findings will be reported at local, national and international conferences and in peer-reviewed journals.
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Affiliation(s)
- Stephanie L. Enkel
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, WA, Australia
- Medical School, University of Western Australia, Crawley, WA, Australia
| | - Thel K. Hla
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, WA, Australia
- Medical School, University of Western Australia, Crawley, WA, Australia
- Department of Infectious Diseases, Fiona Stanley Hospital, Murdoch, WA, Australia
| | - Bernadette Wong
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, WA, Australia
| | - Janessa Pickering
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, WA, Australia
- Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Nedlands, WA, Australia
| | - Timothy C. Barnett
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, WA, Australia
- Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Nedlands, WA, Australia
| | - Hannah M. M. Thomas
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, WA, Australia
| | - Nina Lansbury
- School of Public Health, University of Queensland, Brisbane, QLD, Australia
| | - Jonathan R. Carapetis
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, WA, Australia
- Medical School, University of Western Australia, Crawley, WA, Australia
- Department of Infectious Diseases, Perth Children’s Hospital, Nedlands, WA, Australia
| | - Laurens Manning
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, WA, Australia
- Medical School, University of Western Australia, Crawley, WA, Australia
- Department of Infectious Diseases, Fiona Stanley Hospital, Murdoch, WA, Australia
| | - Asha C. Bowen
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Nedlands, WA, Australia
- Medical School, University of Western Australia, Crawley, WA, Australia
- School of Public Health, University of Queensland, Brisbane, QLD, Australia
- Menzies School of Health Research, Darwin, NT, Australia
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7
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Brazzoli M, Piccioli D, Marchetti F. Challenges in development of vaccines directed toward antimicrobial resistant bacterial species. Hum Vaccin Immunother 2023; 19:2228669. [PMID: 37449650 DOI: 10.1080/21645515.2023.2228669] [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: 04/28/2023] [Revised: 06/05/2023] [Accepted: 06/20/2023] [Indexed: 07/18/2023] Open
Abstract
Antimicrobial resistance (AMR) is considered by WHO one of the top ten public health threats. New control strategies involving concerted actions of both public and private sectors need to be developed. Vaccines play a major role in controlling the spread of AMR pathogens by decreasing transmission and limiting the use of antibiotics, reducing at the end the selective pressure for the emergence of new resistant strains. In this review, by using as example some of the most serious AMR pathogens, we highlighted the major hurdles from a research and development point of view. New approaches to better understand the immunological mechanisms of response to both natural infections and vaccines that aimed to identify correlates of protection, together with the application of new technologies for vaccine design and delivery are discussed as potential solutions.
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8
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Abaasa A, Egesa M, Driciru E, Koopman JPR, Kiyemba R, Sanya RE, Nassuuna J, Ssali A, Kimbugwe G, Wajja A, van Dam GJ, Corstjens PLAM, Cose S, Seeley J, Kamuya D, Webb EL, Yazdanbakhsh M, Kaleebu P, Siddiqui AA, Kabatereine N, Tukahebwa E, Roestenberg M, Elliott AM. Establishing a single-sex controlled human Schistosoma mansoni infection model for Uganda: protocol for safety and dose-finding trial. IMMUNOTHERAPY ADVANCES 2023; 3:ltad010. [PMID: 37538934 PMCID: PMC10396375 DOI: 10.1093/immadv/ltad010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 07/13/2023] [Indexed: 08/05/2023] Open
Abstract
Control of schistosomiasis depends on a single drug, praziquantel, with variable cure rates, high reinfection rates, and risk of drug resistance. A vaccine could transform schistosomiasis control. Preclinical data show that vaccine development is possible, but conventional vaccine efficacy trials require high incidence, long-term follow-up, and large sample size. Controlled human infection studies (CHI) can provide early efficacy data, allowing the selection of optimal candidates for further trials. A Schistosoma CHI has been established in the Netherlands but responses to infection and vaccines differ in target populations in endemic countries. We aim to develop a CHI for Schistosoma mansoni in Uganda to test candidate vaccines in an endemic setting. This is an open-label, dose-escalation trial in two populations: minimal, or intense, prior Schistosoma exposure. In each population, participants will be enrolled in sequential dose-escalating groups. Initially, three volunteers will be exposed to 10 cercariae. If all show infection, seven more will be exposed to the same dose. If not, three volunteers in subsequent groups will be exposed to higher doses (20 or 30 cercariae) following the same algorithm, until all 10 volunteers receiving a particular dose become infected, at which point the study will be stopped for that population. Volunteers will be followed weekly after infection until CAA positivity or to 12 weeks. Once positive, they will be treated with praziquantel and followed for one year. The trial registry number is ISRCTN14033813 and all approvals have been obtained. The trial will be subjected to monitoring, inspection, and/or audits.
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Affiliation(s)
- Andrew Abaasa
- MRC/UVRI & LSHTM Uganda Research Unit, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, London, UK
| | - Moses Egesa
- MRC/UVRI & LSHTM Uganda Research Unit, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, London, UK
| | | | | | | | - Richard E Sanya
- MRC/UVRI & LSHTM Uganda Research Unit, Entebbe, Uganda
- African Population and Health Research Center, Nairobi, Kenya
| | | | - Agnes Ssali
- MRC/UVRI & LSHTM Uganda Research Unit, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, London, UK
| | | | - Anne Wajja
- MRC/UVRI & LSHTM Uganda Research Unit, Entebbe, Uganda
| | | | | | - Stephen Cose
- MRC/UVRI & LSHTM Uganda Research Unit, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, London, UK
| | - Janet Seeley
- MRC/UVRI & LSHTM Uganda Research Unit, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, London, UK
| | - Dorcas Kamuya
- Kenya Medical Research Institute (KEMRI), Kilifi, Kenya
| | - Emily L Webb
- London School of Hygiene & Tropical Medicine, London, UK
| | | | - Pontiano Kaleebu
- MRC/UVRI & LSHTM Uganda Research Unit, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, London, UK
| | | | | | | | | | - Alison M Elliott
- MRC/UVRI & LSHTM Uganda Research Unit, Entebbe, Uganda
- London School of Hygiene & Tropical Medicine, London, UK
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9
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Buggert M, Price DA, Mackay LK, Betts MR. Human circulating and tissue-resident memory CD8 + T cells. Nat Immunol 2023:10.1038/s41590-023-01538-6. [PMID: 37349380 DOI: 10.1038/s41590-023-01538-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 05/04/2023] [Indexed: 06/24/2023]
Abstract
Our current knowledge of human memory CD8+ T cells is derived largely from studies of the intravascular space. However, emerging data are starting to challenge some of the dogmas based on this work, suggesting that a conceptual revision may be necessary. In this review, we provide a brief history of the field and summarize the biology of circulating and tissue-resident memory CD8+ T cells, which are ultimately responsible for effective immune surveillance. We also incorporate recent findings into a biologically integrated model of human memory CD8+ T cell differentiation. Finally, we address how future innovative human studies could improve our understanding of anatomically localized CD8+ T cells to inform the development of more effective immunotherapies and vaccines, the need for which has been emphasized by the global struggle to contain severe acute respiratory syndrome coronavirus 2.
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Affiliation(s)
- Marcus Buggert
- Center for Infectious Medicine, Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden.
| | - David A Price
- Division of Infection and Immunity, Cardiff University School of Medicine, Cardiff, UK
- Systems Immunity Research Institute, Cardiff University School of Medicine, Cardiff, UK
| | - Laura K Mackay
- Department of Microbiology and Immunology, The University of Melbourne at The Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Michael R Betts
- Institute for Immunology and Center for AIDS Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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10
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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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11
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Dabira ED, Fehr A, Beloum N, Van Geertruyden JP, Achan J, Erhart A, Martinez-Alvarez M, D'Alessandro U. Perceptions and acceptability of the controlled human malaria infection (CHMI) model in The Gambia: a qualitative study. Sci Rep 2023; 13:8708. [PMID: 37248260 DOI: 10.1038/s41598-023-35752-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 05/23/2023] [Indexed: 05/31/2023] Open
Abstract
Controlled human malaria infection (CHMI) studies, i.e. the deliberate infection of healthy volunteers with malaria parasites to study immune response and/or test drug or vaccine efficacy, are increasingly being conducted in malaria endemic countries, including in sub-Saharan Africa. However, there have been few studies on the perceptions and acceptability of CHMI by the local communities. This qualitative study assessed the perception and acceptability of such studies in The Gambia following the first CHMI study conducted in the country in March-May 2018. Data were collected through non-participant observation, in-depth interviews and focus group discussions and analyzed using NVivo 12 software with an inductive-deductive approach. Sixty-seven participants were involved, including volunteers enrolled in the CHMI, community stakeholders and members of the Gambian Ethics Committee. Respondents expressed a positive view about CHMI. Key motivating factors for participation were the financial compensation, comprehensive health checks, and willingness to support malaria research. Risks associated with participation were considered low. Concerns raised included the frequency of bleeding and the blood volume collected.
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Affiliation(s)
- Edgard Diniba Dabira
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine (MRCG at LSHTM), Fajara, The Gambia.
- Global Health Institute, Faculty of Medicine and Health Sciences, University of Antwerp, Wilrijk, Belgium.
| | - Alexandra Fehr
- London School of Hygiene and Tropical Medicine, London, UK
| | - Nathalie Beloum
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine (MRCG at LSHTM), Fajara, The Gambia
| | | | | | - Annette Erhart
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine (MRCG at LSHTM), Fajara, The Gambia
| | - Melisa Martinez-Alvarez
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine (MRCG at LSHTM), Fajara, The Gambia
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine (MRCG at LSHTM), Fajara, The Gambia
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12
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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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13
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Schnyder JL, de Jong HK, Bache EB, van Hest RM, Schlagenhauf P, Borrmann S, Hanscheid T, Grobusch MP. On the potential for discontinuing atovaquone-proguanil (AP) ad-hoc post-exposure and other abbreviated AP-regimens: Pharmacology, pharmacokinetics and perspectives. Travel Med Infect Dis 2022; 52:102520. [PMID: 36526126 DOI: 10.1016/j.tmaid.2022.102520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/30/2022] [Accepted: 12/09/2022] [Indexed: 12/15/2022]
Abstract
According to current guidelines, atovaquone-proguanil (AP) malaria chemoprophylaxis should be taken once daily starting one day before travel and continued for seven days post-exposure. However, drug-sparing regimens, including discontinuing AP after leaving malaria-endemic areas are cost-saving and probably more attractive to travelers, and may thus enhance adherence. AP has causal prophylactic effects, killing malaria parasites during the hepatic stage. If early hepatic stages were already targeted by AP, AP could possibly be discontinued upon return. Pharmacokinetic data and studies on drug-sparing AP regimens suggest this to be the case. Nevertheless, the evidence is weak and considered insufficient to modify current recommendations. Field trials require large numbers of travelers and inherently suffer from the lack of a control group. Safely-designed controlled human malaria infection trials could significantly reduce study participant numbers and safely establish an effective AP abbreviated regimen which we propose as the optimal trial design to test this concept.
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Affiliation(s)
- Jenny L Schnyder
- Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam UMC, Location University of Amsterdam, Amsterdam, Netherlands
| | - Hanna K de Jong
- Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam UMC, Location University of Amsterdam, Amsterdam, Netherlands
| | - Emmanuel B Bache
- Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam UMC, Location University of Amsterdam, Amsterdam, Netherlands
| | - Reinier M van Hest
- Department of Hospital Pharmacy & Clinical Pharmacology, Amsterdam UMC, Location University of Amsterdam, Amsterdam, Netherlands
| | - Patricia Schlagenhauf
- University of Zurich Centre for Travel Medicine, WHO Collaborating Centre for Travelers' Health, Department of Public and Global Health, Military Medicine Biology Competence Centre, Institute for Epidemiology, Biostatistics and Prevention, Zurich, Switzerland
| | - Steffen Borrmann
- Institute of Tropical Medicine, German Centre for Infection Research (DZIF), University of Tübingen, Tübingen, Germany; Centre de Recherches Médicales en Lambaréné (CERMEL), Lambaréné, Gabon
| | - Thomas Hanscheid
- Instituto de Microbiologia, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Martin P Grobusch
- Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam UMC, Location University of Amsterdam, Amsterdam, Netherlands; Institute of Tropical Medicine, German Centre for Infection Research (DZIF), University of Tübingen, Tübingen, Germany; Centre de Recherches Médicales en Lambaréné (CERMEL), Lambaréné, Gabon; Masanga Medical Research Unit (MMRU), Masanga, Sierra Leone; Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town, South Africa.
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14
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Abstract
Since the identification of sickle cell trait as a heritable form of resistance to malaria, candidate gene studies, linkage analysis paired with sequencing, and genome-wide association (GWA) studies have revealed many examples of genetic resistance and susceptibility to infectious diseases. GWA studies enabled the identification of many common variants associated with small shifts in susceptibility to infectious diseases. This is exemplified by multiple loci associated with leprosy, malaria, HIV, tuberculosis, and coronavirus disease 2019 (COVID-19), which illuminate genetic architecture and implicate pathways underlying pathophysiology. Despite these successes, most of the heritability of infectious diseases remains to be explained. As the field advances, current limitations may be overcome by applying methodological innovations such as cellular GWA studies and phenome-wide association (PheWA) studies as well as by improving methodological rigor with more precise case definitions, deeper phenotyping, increased cohort diversity, and functional validation of candidate loci in the laboratory or human challenge studies.
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Affiliation(s)
- Kyle D Gibbs
- Department of Molecular Genetics and Microbiology, School of Medicine, Duke University, Durham, North Carolina, USA;
| | - Benjamin H Schott
- Department of Molecular Genetics and Microbiology, School of Medicine, Duke University, Durham, North Carolina, USA; .,Duke University Program in Genetics and Genomics, Duke University, Durham, North Carolina, USA
| | - Dennis C Ko
- Department of Molecular Genetics and Microbiology, School of Medicine, Duke University, Durham, North Carolina, USA; .,Duke University Program in Genetics and Genomics, Duke University, Durham, North Carolina, USA.,Division of Infectious Diseases, Department of Medicine, School of Medicine, Duke University, Durham, North Carolina, USA
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15
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Sztein MB, Booth JS. Controlled human infectious models, a path forward in uncovering immunological correlates of protection: Lessons from enteric fevers studies. Front Microbiol 2022; 13:983403. [PMID: 36204615 PMCID: PMC9530043 DOI: 10.3389/fmicb.2022.983403] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/24/2022] [Indexed: 11/13/2022] Open
Abstract
Enteric infectious diseases account for more than a billion disease episodes yearly worldwide resulting in approximately 2 million deaths, with children under 5 years old and the elderly being disproportionally affected. Enteric pathogens comprise viruses, parasites, and bacteria; the latter including pathogens such as Salmonella [typhoidal (TS) and non-typhoidal (nTS)], cholera, Shigella and multiple pathotypes of Escherichia coli (E. coli). In addition, multi-drug resistant and extensively drug-resistant (XDR) strains (e.g., S. Typhi H58 strain) of enteric bacteria are emerging; thus, renewed efforts to tackle enteric diseases are required. Many of these entero-pathogens could be controlled by oral or parenteral vaccines; however, development of new, effective vaccines has been hampered by lack of known immunological correlates of protection (CoP) and limited knowledge of the factors contributing to protective responses. To fully comprehend the human response to enteric infections, an invaluable tool that has recently re-emerged is the use of controlled human infection models (CHIMs) in which participants are challenged with virulent wild-type (wt) organisms. CHIMs have the potential to uncover immune mechanisms and identify CoP to enteric pathogens, as well as to evaluate the efficacy of therapeutics and vaccines in humans. CHIMs have been used to provide invaluable insights in the pathogenesis, host-pathogen interaction and evaluation of vaccines. Recently, several Oxford typhoid CHIM studies have been performed to assess the role of multiple cell types (B cells, CD8+ T, Tregs, MAIT, Monocytes and DC) during S. Typhi infection. One of the key messages that emerged from these studies is that baseline antigen-specific responses are important in that they can correlate with clinical outcomes. Additionally, volunteers who develop typhoid disease (TD) exhibit higher levels and more activated cell types (e.g., DC and monocytes) which are nevertheless defective in discrete signaling pathways. Future critical aspects of this research will involve the study of immune responses to enteric infections at the site of entry, i.e., the intestinal mucosa. This review will describe our current knowledge of immunity to enteric fevers caused byS. Typhi and S. Paratyphi A, with emphasis on the contributions of CHIMs to uncover the complex immunological responses to these organisms and provide insights into the determinants of protective immunity.
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Affiliation(s)
- Marcelo B. Sztein
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, United States
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
- *Correspondence: Marcelo B. Sztein,
| | - Jayaum S. Booth
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, United States
- Jayaum S. Booth,
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16
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Barnes E, Cooke GS, Lauer GM, Chung RT. Implementation of a controlled human infection model for evaluation of HCV vaccine candidates. Hepatology 2022; 77:1757-1772. [PMID: 35736236 DOI: 10.1002/hep.32632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 06/08/2022] [Accepted: 06/10/2022] [Indexed: 12/08/2022]
Abstract
Hepatitis C virus (HCV) remains a major global health concern. Directly acting antiviral (DAA) drugs have transformed the treatment of HCV. However, it has become clear that, without an effective HCV vaccine, it will not be possible to meet the World Health Organization targets of HCV viral elimination. Promising new vaccine technologies that generate high magnitude antiviral T and B cell immune responses and significant new funding have recently become available, stimulating the HCV vaccine pipeline. In the absence of an immune competent animal model for HCV, the major block in evaluating new HCV vaccine candidates will be the assessment of vaccine efficacy in humans. The development of a controlled human infection model (CHIM) for HCV could overcome this block, enabling the head-to-head assessment of vaccine candidates. The availability of highly effective DAA means that a CHIM for HCV is possible for the first time. In this review, we highlight the challenges and issues with currently available strategies to assess HCV vaccine efficacy including HCV "at-risk" cohorts and animal models. We describe the development of CHIM in other infections that are increasingly utilized by trialists and explore the ethical and safety concerns specific for an HCV CHIM. Finally, we propose an HCV CHIM study design including the selection of volunteers, the development of an infectious inoculum, the evaluation of host immune and viral parameters, and the definition of study end points for use in an HCV CHIM. Importantly, the study design (including number of volunteers required, cost, duration of study, and risk to volunteers) varies significantly depending on the proposed mechanism of action (sterilizing/rapid viral clearance vs. delayed viral clearance) of the vaccine under evaluation. We conclude that an HCV CHIM is now realistic, that safety and ethical concerns can be addressed with the right study design, and that, without an HCV CHIM, it is difficult to envisage how the development of an HCV vaccine will be possible.
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Affiliation(s)
- Eleanor Barnes
- Peter Medawar Building for Pathogen Research, Nuffield Department of Medicine, Oxford, UK
| | - Graham S Cooke
- Department of Infectious Disease, Imperial College London, Oxford, UK
| | - Georg M Lauer
- Liver Center, GI Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Raymond T Chung
- Liver Center, GI Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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17
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Dayananda P, Chiu C, Openshaw P. Controlled Human Infection Challenge Studies with RSV. Curr Top Microbiol Immunol 2022. [PMID: 35704096 DOI: 10.1007/82_2022_257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Despite considerable momentum in the development of RSV vaccines and therapeutics, there remain substantial barriers to the development and licensing of effective agents, particularly in high-risk populations. The unique immunobiology of RSV and lack of clear protective immunological correlates has held back RSV vaccine development, which, therefore, depends on large and costly clinical trials to demonstrate efficacy. Studies involving the deliberate infection of human volunteers offer an intermediate step between pre-clinical and large-scale studies of natural infection. Human challenge has been used to demonstrate the potential efficacy of vaccines and antivirals while improving our understanding of the protective immunity against RSV infection. Early RSV human infection challenge studies determined the role of routes of administration and size of inoculum on the disease. However, inherent limitations, the use of highly attenuated/laboratory-adapted RSV strains and the continued evolutionary adaptation of RSV limits extrapolation of results to present-day vaccine testing. With advances in technology, it is now possible to perform more detailed investigations of human mucosal immunity against RSV in experimentally infected adults and, more recently, older adults to optimise the design of vaccines and novel therapies. These studies identified defects in RSV-induced humoral and CD8+ T cell immunity that may partly explain susceptibility to recurrent RSV infection. We discuss the insights from human infection challenge models, ethical and logistical considerations, potential benefits, and role in streamlining and accelerating novel antivirals and vaccines against RSV. Finally, we consider how human challenges might be extended to include relevant at-risk populations.
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Affiliation(s)
- Pete Dayananda
- Department of Infectious Disease, Imperial College London, London, UK
| | - Christopher Chiu
- Department of Infectious Disease, Imperial College London, London, UK.
| | - Peter Openshaw
- National Heart and Lung Institute, Imperial College London, London, UK
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18
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Schnyder JL, de Jong HK, Schlagenhauf P, Borrmann S, Hanscheid T, Grobusch MP. Discontinuing atovaquone/proguanil prophylaxis ad-hoc post-exposure and during-travel dose-sparing prophylactic regimens against P. falciparum malaria: An update with pointers for future research. Travel Med Infect Dis 2022; 49:102365. [PMID: 35661741 DOI: 10.1016/j.tmaid.2022.102365] [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: 05/03/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 11/27/2022]
Abstract
BACKGROUND Atovaquone/proguanil (AP) is a highly effective malaria chemoprophylaxis combination. According to current guidelines, AP is taken once daily during, and continued for seven days post exposure. A systematic review by Savelkoel et al. summarised data up to 2017 on abbreviated AP regimens, and concluded that discontinuing AP upon return may be effective, although the available data was insufficient to modify current recommendations. The same applies to other studies evaluating during-travel dose-sparing regimens. METHODS A literature search in Pubmed and Embase was performed including search terms related to AP prophylaxis and pharmacokinetics to search for recent studies on abbreviated AP regimens published since 2017. RESULTS Since the 2017 review, no new studies assessing discontinuing AP ad-hoc post-exposure prophylaxis have been published. Two new studies were identified assessing other abbreviated AP regimens; one investigated a twice-weekly AP regimen in 32 travellers, and one a three-day AP course in therapeutic dose (1000/400 mg) prior to exposure in 215 travellers. No malaria cases were detected in the study participants adhering to these regimens. CONCLUSIONS Further research would be needed if the research question is considered of sufficient importance to facilitate evidence-based decision-making to modify current guidelines, as efficacy studies in travellers are fraught with confounders. We recommend human challenge trials to study abbreviated AP regimens pertaining to malaria chemoprophylaxis as they allow for rational, subject number, time- and cost-saving trial designs.
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Affiliation(s)
- Jenny L Schnyder
- Centre for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam UMC, Location University of Amsterdam, Amsterdam, Netherlands
| | - Hanna K de Jong
- Centre for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam UMC, Location University of Amsterdam, Amsterdam, Netherlands
| | - Patricia Schlagenhauf
- University of Zurich Centre for Travel Medicine, WHO Collaborating Centre for Travellers' Health, Department of Public and Global Health, Military Medicine Biology Competence Centre, Institute for Epidemiology, Biostatistics and Prevention, Zurich, Switzerland
| | - Steffen Borrmann
- Institute of Tropical Medicine, German Centre for Infection Research (DZIF), University of Tübingen, Tübingen, Germany
| | - Thomas Hanscheid
- Instituto de Microbiologia, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Martin P Grobusch
- Centre for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam UMC, Location University of Amsterdam, Amsterdam, Netherlands; Institute of Tropical Medicine, German Centre for Infection Research (DZIF), University of Tübingen, Tübingen, Germany; Centre de Recherches Médicales en Lambaréné (CERMEL), Lambaréné, Gabon; Masanga Medical Research Unit (MMRU), Masanga, Gabon; Institute of Infectious Diseases and Molecular Medicine (IDM), University of Cape Town, Cape Town, South Africa.
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19
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Fakoya B, Hullahalli K, Rubin DHF, Leitner DR, Chilengi R, Sack DA, Waldor MK. Nontoxigenic Vibrio cholerae Challenge Strains for Evaluating Vaccine Efficacy and Inferring Mechanisms of Protection. mBio 2022; 13:e0053922. [PMID: 35389261 PMCID: PMC9040834 DOI: 10.1128/mbio.00539-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 12/24/2022] Open
Abstract
Human challenge studies are instrumental for testing cholera vaccines, but these studies use outdated strains and require inpatient facilities. Here, we created next-generation isogenic Ogawa and Inaba O1 V. cholerae challenge strains (ZChol strains) derived from a contemporary Zambian clinical isolate representative of current dominant pandemic V. cholerae. Since the primary mechanism of immune protection against cholera is thought to be antibody responses that limit V. cholerae colonization and not the diarrheagenic actions of cholera toxin, these strains were rendered nontoxigenic. In infant mice, the ZChol strains did not cause diarrhea and proved to accurately gauge reduction in intestinal colonization mediated by effective vaccination. ZChol strains were also valuable as targets for measuring vibriocidal antibody responses. Using barcoded ZChol strains, we discovered that vaccination and passive immunity in the infant mouse model tightens the infection bottleneck without restricting pathogen expansion during intestinal infection. Collectively, our findings suggest that ZChol strains have the potential to enhance the safety, relevance, and scope of future cholera vaccine challenge studies and be valuable reagents for studies of immunity to cholera. IMPORTANCE Human challenge studies are a valuable method for testing the efficacy of cholera vaccines. However, challenge studies cannot be performed in countries of cholera endemicity due to safety concerns; also, contemporary pandemic Vibrio cholerae strains are not used in current challenge studies. To facilitate cholera research, we derived nontoxigenic challenge strains of both V. cholerae serotypes from a 2016 clinical isolate from Zambia and demonstrated how they can be used to gauge cholera immunity accurately and safely. These strains were also genetically barcoded, adding the potential for analyses of V. cholerae population dynamics to challenge studies. Preclinical analyses presented here suggest that these strains have the potential to enhance the safety, relevance, and scope of future cholera vaccine challenge studies and be valuable reagents for studies of immunity to cholera.
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Affiliation(s)
- Bolutife Fakoya
- Division of Infectious Diseases, Brigham & Women’s Hospital, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Bethesda, Maryland, USA
| | - Karthik Hullahalli
- Division of Infectious Diseases, Brigham & Women’s Hospital, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Bethesda, Maryland, USA
| | - Daniel H. F. Rubin
- Division of Infectious Diseases, Brigham & Women’s Hospital, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Bethesda, Maryland, USA
| | - Deborah R. Leitner
- Division of Infectious Diseases, Brigham & Women’s Hospital, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Bethesda, Maryland, USA
| | - Roma Chilengi
- Enteric Disease and Vaccine Research Unit, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - David A. Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Matthew K. Waldor
- Division of Infectious Diseases, Brigham & Women’s Hospital, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Bethesda, Maryland, USA
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20
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Affiliation(s)
- Kathryn M Edwards
- Division of Infectious Diseases, Department of Pediatrics, Monroe Carell Jr Children's Hospital at Vanderbilt, Vanderbilt University School of Medicine, Nashville, TN, USA.
| | - Kathleen M Neuzil
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
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21
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Msusa KP, Rogalski-Salter T, Mandi H, Clemens R. Critical success factors for conducting human challenge trials for vaccine development in low- and middle-income countries. Vaccine 2022; 40:1261-1270. [PMID: 35101267 DOI: 10.1016/j.vaccine.2022.01.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 01/10/2022] [Accepted: 01/19/2022] [Indexed: 12/22/2022]
Abstract
BACKGROUND Owing to the globalization of vaccine clinical trials, as well as advances in technologies, improved research accountability, and robust regulatory and ethical scrutiny, the choice to perform human challenge trials has become evident, and one of the most significant applications of human challenge trials is the assessment of vaccine efficacy. While human challenge trials have largely been conducted in high-income countries, the concept is relatively new in many low- and middle-income countries. Thus, the aim of this study was to identify the critical success factors for conducting human challenge trials for vaccine development in low- and middle-income countries. METHODOLOGY Using a two-step methodology, we first carried out a systematic literature review that was centered on identifying low- and middle-income countries that are either establishing a framework for, have conducted, or are conducting human challenge trials for vaccine development; secondly, we conducted a descriptive cross-sectional survey using a standardized semi-structured online questionnaire administered to eligible stakeholders, to identify the critical success factors for conducting human challenge trials for vaccine development in low- and middle-income countries. Seventeen low- and middle-income countries were identified and included in the survey. RESULTS The most cited critical success factors for conducting human challenge trials for vaccine development in low- and middle-income countries were Informed Consent, Risk Compensation and/or Reimbursement, Participant Safety and/or Public Protection, Community Engagement, Infrastructural Capacity, and Ethical and Regulatory Frameworks. CONCLUSION From an empirical perspective, this study provides a list of critical success factors that form the basic structure to guide the design and implementation of further human challenge trials in low- and middle-income countries. Further studies are needed to establish a standardized conceptual framework to aid in the review, approval and overall conduct of human challenge trials in low- and middle-income countries.
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Affiliation(s)
- Keiko Pempho Msusa
- University of Siena, Institute for Global Health, Santa Chiara Lab, Via Val di Montone, 1, 53100 Siena, SI, Italy.
| | - Taryn Rogalski-Salter
- Bill and Melinda Gates Medical Research Institute (Gates MRI), Cambridge, MA, United States
| | - Henshaw Mandi
- Coalition for Epidemic Preparedness Innovations (CEPI), Marcus Thranes Gate 2, 0473 Oslo, Norway
| | - Ralf Clemens
- University of Siena, Institute for Global Health, Santa Chiara Lab, Via Val di Montone, 1, 53100 Siena, SI, Italy
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22
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Barker C, Collet K, Gbesemete D, Piggin M, Watson D, Pristerà P, Lawerence W, Smith E, Bahrami-Hessari M, Johnson H, Baker K, Qavi A, McGrath C, Chiu C, Read RC, Ward H. Public attitudes to a human challenge study with SARS-CoV-2: a mixed-methods study. Wellcome Open Res 2022; 7:49. [PMID: 35321005 PMCID: PMC8921687 DOI: 10.12688/wellcomeopenres.17516.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2022] [Indexed: 11/20/2022] Open
Abstract
Background: Human challenge studies involve the deliberate exposure of healthy volunteers to an infectious micro-organism in a highly controlled and monitored way. They are used to understand infectious diseases and have contributed to the development of vaccines. In early 2020, the UK started exploring the feasibility of establishing a human challenge study with SARS-CoV-2. Given the significant public interest and the complexity of the potential risks and benefits, it is vital that public views are considered in the design and approval of any such study and that investigators and ethics boards remain accountable to the public. Methods: Mixed methods study comprising online surveys conducted with 2,441 UK adults and in-depth virtual focus groups with 57 UK adults during October 2020 to explore the public's attitudes to a human challenge study with SARS-CoV-2 taking place in the UK. Results: There was overall agreement across the surveys and focus groups that a human challenge study with SARS-CoV-2 should take place in the UK. Transparency of information, trust and the necessity to provide clear information on potential risks to study human challenge study participants were important. The perceived risks of taking part included the risk of developing long-term effects from COVID, impact on personal commitments and mental health implications of isolation. There were a number of practical realities to taking part that would influence a volunteer's ability to participate (e.g. Wi-Fi, access to exercise, outside space and work, family and pet commitments). Conclusions: The results identified practical considerations for teams designing human challenge studies. Recommendations were grouped: 1) messaging to potential study participants, 2) review of the protocol and organisation of the study, and 3) more broadly, making the study more inclusive and relevant. This study highlights the value of public consultation in research, particularly in fields attracting public interest and scrutiny .
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Affiliation(s)
- Caroline Barker
- NIHR Southampton Clinical Research Facility and NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
- NIHR Applied Research Collaboration Wessex, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK, UK
| | - Katharine Collet
- NIHR Imperial Biomedical Research Centre, Patient Experience Research Centre, Imperial College London, London, W2 1NY, UK
| | - Diane Gbesemete
- NIHR Southampton Clinical Research Facility and NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
- School of Clinical and Experimental Sciences, Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, S016 6YD, UK
| | - Maria Piggin
- NIHR Imperial Biomedical Research Centre, Patient Experience Research Centre, Imperial College London, London, W2 1NY, UK
| | - Daniella Watson
- MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, S016 6YD, UK
| | - Philippa Pristerà
- NIHR Imperial Biomedical Research Centre, Patient Experience Research Centre, Imperial College London, London, W2 1NY, UK
| | - Wendy Lawerence
- NIHR Southampton Clinical Research Facility and NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
- Global Health Research Institute, School of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, SO17 1BJ, UK
| | - Emma Smith
- National Heart and Lung Institute, Imperial College London, London, W2 1NY, UK
| | - Michael Bahrami-Hessari
- NIHR Southampton Clinical Research Facility and NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - Halle Johnson
- NIHR Imperial Biomedical Research Centre, Patient Experience Research Centre, Imperial College London, London, W2 1NY, UK
| | - Katherine Baker
- NIHR Applied Research Collaboration Wessex, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK, UK
| | - Ambar Qavi
- NIHR Imperial Biomedical Research Centre, Patient Experience Research Centre, Imperial College London, London, W2 1NY, UK
| | - Carmel McGrath
- NIHR Southampton Clinical Research Facility and NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
- School of Clinical and Experimental Sciences, Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, S016 6YD, UK
| | - Christopher Chiu
- Department of Infectious Diseases, Imperial College London, London, W2 1NY, UK
| | - Robert C. Read
- NIHR Southampton Clinical Research Facility and NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
- School of Clinical and Experimental Sciences, Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, S016 6YD, UK
| | - Helen Ward
- NIHR Imperial Biomedical Research Centre, Patient Experience Research Centre, Imperial College London, London, W2 1NY, UK
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Hamady A, Lee J, Loboda ZA. Waning antibody responses in COVID-19: what can we learn from the analysis of other coronaviruses? Infection 2022; 50:11-25. [PMID: 34324165 PMCID: PMC8319587 DOI: 10.1007/s15010-021-01664-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 07/08/2021] [Indexed: 12/16/2022]
Abstract
OBJECTIVES The coronavirus disease 2019 (COVID-19), caused by the novel betacoronavirus severe acute respiratory syndrome 2 (SARS-CoV-2), was declared a pandemic in March 2020. Due to the continuing surge in incidence and mortality globally, determining whether protective, long-term immunity develops after initial infection or vaccination has become critical. METHODS/RESULTS In this narrative review, we evaluate the latest understanding of antibody-mediated immunity to SARS-CoV-2 and to other coronaviruses (SARS-CoV, Middle East respiratory syndrome coronavirus and the four endemic human coronaviruses) in order to predict the consequences of antibody waning on long-term immunity against SARS-CoV-2. We summarise their antibody dynamics, including the potential effects of cross-reactivity and antibody waning on vaccination and other public health strategies. At present, based on our comparison with other coronaviruses we estimate that natural antibody-mediated protection for SARS-CoV-2 is likely to last for 1-2 years and therefore, if vaccine-induced antibodies follow a similar course, booster doses may be required. However, other factors such as memory B- and T-cells and new viral strains will also affect the duration of both natural and vaccine-mediated immunity. CONCLUSION Overall, antibody titres required for protection are yet to be established and inaccuracies of serological methods may be affecting this. We expect that with standardisation of serological testing and studies with longer follow-up, the implications of antibody waning will become clearer.
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Affiliation(s)
- Ali Hamady
- Department of Immunology and Inflammation, Imperial College London, London, UK
| | - JinJu Lee
- Department of Immunology and Inflammation, Imperial College London, London, UK
| | - Zuzanna A Loboda
- Department of Immunology and Inflammation, Imperial College London, London, UK.
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24
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Sit B, Fakoya B, Waldor MK. Animal models for dissecting Vibrio cholerae intestinal pathogenesis and immunity. Curr Opin Microbiol 2022; 65:1-7. [PMID: 34695646 PMCID: PMC8792189 DOI: 10.1016/j.mib.2021.09.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/14/2021] [Accepted: 09/20/2021] [Indexed: 02/03/2023]
Abstract
The human diarrheal disease cholera is caused by the bacterium Vibrio cholerae. Efforts to develop animal models that closely mimic cholera to study the pathogenesis of this disease began >125 years ago. Here, we review currently used non-surgical, oral inoculation-based animal models for investigation of V. cholerae intestinal colonization and disease and highlight recent discoveries that have illuminated mechanisms of cholera pathogenesis and immunity, particularly in the area of how V. cholerae interacts with the gut microbiome to influence infection. The emergence of high-throughput tools for studies of pathogen-host interactions, along with continued advances in host genetic engineering and manipulation in animal models of V. cholerae will deepen understanding of cholera pathogenesis, uncovering knowledge important for control of this globally important bacterial pathogen.
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Affiliation(s)
- Brandon Sit
- Division of Infectious Diseases, Brigham and Women’s Hospital, Boston, Massachusetts, USA,Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Bolutife Fakoya
- Division of Infectious Diseases, Brigham and Women’s Hospital, Boston, Massachusetts, USA,Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Matthew K. Waldor
- Division of Infectious Diseases, Brigham and Women’s Hospital, Boston, Massachusetts, USA,Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Massachusetts, USA,Howard Hughes Medical Institute, Bethesda, Maryland, USA,corresponding author: , Phone: 6175254646, Address: MCP-759, 181 Longwood Avenue, Boston, Massachusetts, USA 02115
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25
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Stamps BW, Kuroiwa J, Isidean SD, Schilling MA, Harro C, Talaat KR, Sack DA, Tribble DR, Maue AC, Rimmer JE, Laird RM, Porter CK, Goodson MS, Poly F. Exploring Changes in the Host Gut Microbiota During a Controlled Human Infection Model for Campylobacter jejuni. Front Cell Infect Microbiol 2021; 11:702047. [PMID: 34532299 PMCID: PMC8439579 DOI: 10.3389/fcimb.2021.702047] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 08/13/2021] [Indexed: 01/02/2023] Open
Abstract
Campylobacter jejuni infection is a leading cause of foodborne disease, common to children, adult travelers, and military populations in low- to middle-income countries. In the absence of a licensed vaccine, efforts to evaluate prophylactic agents are underway. The prophylactic efficacy of a twice-daily, 550 mg dose of the antibiotic rifaximin demonstrated no efficacy against campylobacteriosis in a controlled human infection model (CHIM); however, samples from the CHIM study were utilized to assess how the human gut microbiome responds to C. jejuni infection, and if a ‘protective’ microbiota exists in study participants not developing campylobacteriosis. Statistically significant, but minor, differences in study participant beta diversity were identified during the challenge period (p = 0.002, R2 = 0.042), but no significant differences were otherwise observed. Pre-challenge alpha diversity was elevated in study participants who did not develop campylobacteriosis compared to those who did (p < 0.001), but alpha diversity declined in all study participants from the pre-challenge period to post-discharge. Our work provides insight into gut microbiome shifts observed during a C. jejuni CHIM and following antibiotic treatment. This study utilized a high dose of 1.7 x 105 colony-forming units of C. jejuni; future work could include CHIM studies performed with inocula more closely mimicking natural exposure as well as field studies involving naturally-occurring enteric infections.
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Affiliation(s)
- Blake W Stamps
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH, United States.,Integrative Health and Performance Sciences Division, UES, Inc., Dayton, OH, United States
| | - Janelle Kuroiwa
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States
| | - Sandra D Isidean
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States
| | - Megan A Schilling
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
| | - Clayton Harro
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Kawsar R Talaat
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - David A Sack
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - David R Tribble
- Infectious Disease Clinical Research Program, Preventive Medicine and Biostatistics Department, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Alexander C Maue
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States
| | - Joanna E Rimmer
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States.,Academic Department of Military Medicine, Royal Centre for Defence Medicine, Medical Directorate, Joint Medical Command, Information and Communications Technology Centre, Birmingham, United Kingdom
| | - Renee M Laird
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States
| | - Chad K Porter
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
| | - Michael S Goodson
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH, United States
| | - Frédéric Poly
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
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26
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Parkash V, Ashwin H, Sadlova J, Vojtkova B, Jones G, Martin N, Greensted E, Allgar V, Kamhawi S, Valenzuela JG, Layton AM, Jaffe CL, Volf P, Kaye PM, Lacey CJN. A clinical study to optimise a sand fly biting protocol for use in a controlled human infection model of cutaneous leishmaniasis (the FLYBITE study). Wellcome Open Res 2021; 6:168. [PMID: 34693027 PMCID: PMC8506224 DOI: 10.12688/wellcomeopenres.16870.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2021] [Indexed: 02/02/2023] Open
Abstract
Background: Leishmaniasis is a globally important yet neglected parasitic disease transmitted by phlebotomine sand flies. With new candidate vaccines in or near the clinic, a controlled human challenge model (CHIM) using natural sand fly challenge would provide a method for early evaluation of prophylactic efficacy. Methods : We evaluated the biting frequency and adverse effects resulting from exposure of human volunteers to bites of either Phlebotomus papatasi or P. duboscqi, two natural vectors of Leishmania major. 12 healthy participants were recruited (mean age 40.2 ± 11.8 years) with no history of significant travel to regions where L. major-transmitting sand flies are prevalent. Participants were assigned to either vector by 1:1 allocation and exposed to five female sand flies for 30 minutes in a custom biting chamber. Bite frequency was recorded to confirm a bloodmeal was taken. Participant responses and safety outcomes were monitored using a visual analogue scale (VAS), clinical examination, and blood biochemistry. Focus groups were subsequently conducted to explore participant acceptability. Results: All participants had at least one successful sand fly bite with none reporting any serious adverse events, with median VAS scores of 0-1/10 out to day 21 post-sand fly bite. Corresponding assessment of sand flies confirmed that for each participant at least 1/5 sand flies had successfully taken a bloodmeal (overall mean 3.67±1.03 bites per participant). There was no significant difference between P. papatasi and P. duboscqi in the number of bites resulting from 5 sand flies applied to human participants (3.3±0.81 vs 3.00±1.27 bites per participant; p=0.56) . In the two focus groups (n=5 per group), themes relating to positive participant-reported experiences of being bitten and the overall study, were identified. Conclusions: These results validate a protocol for achieving successful sand fly bites in humans that is safe, well-tolerated and acceptable for participants. Clinicaltrials.gov registration: NCT03999970 (27/06/2019).
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Affiliation(s)
- Vivak Parkash
- York Biomedical Research Institute, Hull York Medical School, University of York, York, N.Yorks, YO10 5DD, UK
- Department of Infection and Tropical Medicine, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Helen Ashwin
- York Biomedical Research Institute, Hull York Medical School, University of York, York, N.Yorks, YO10 5DD, UK
| | - Jovana Sadlova
- Department of Parasitology, Charles University, Prague, Czech Republic
| | - Barbora Vojtkova
- Department of Parasitology, Charles University, Prague, Czech Republic
| | - Georgina Jones
- School of Social Sciences, Leeds Beckett University, Leeds, UK
| | - Nina Martin
- School of Social Sciences, Leeds Beckett University, Leeds, UK
| | - Elizabeth Greensted
- York Biomedical Research Institute, Hull York Medical School, University of York, York, N.Yorks, YO10 5DD, UK
| | - Victoria Allgar
- Peninsula Medical School, University of Plymouth, Plymouth, UK
| | - Shaden Kamhawi
- Laboratory of Malaria and Vector Research, National Institutes of Health, Rockville, MD, USA
| | - Jesus G. Valenzuela
- Laboratory of Malaria and Vector Research, National Institutes of Health, Rockville, MD, USA
| | - Alison M. Layton
- York Biomedical Research Institute, Hull York Medical School, University of York, York, N.Yorks, YO10 5DD, UK
| | - Charles L. Jaffe
- Department of Microbiology and Molecular Genetics, The Hebrew University – Hadassah Medical School, Jerusalem, Israel
| | - Petr Volf
- Department of Parasitology, Charles University, Prague, Czech Republic
| | - Paul M. Kaye
- York Biomedical Research Institute, Hull York Medical School, University of York, York, N.Yorks, YO10 5DD, UK
| | - Charles J. N. Lacey
- York Biomedical Research Institute, Hull York Medical School, University of York, York, N.Yorks, YO10 5DD, UK
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27
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Parkash V, Jones G, Martin N, Steigmann M, Greensted E, Kaye P, Layton AM, Lacey CJ. Assessing public perception of a sand fly biting study on the pathway to a controlled human infection model for cutaneous leishmaniasis. RESEARCH INVOLVEMENT AND ENGAGEMENT 2021; 7:33. [PMID: 34053461 PMCID: PMC8164890 DOI: 10.1186/s40900-021-00277-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND A controlled human infection model (CHIM) involves deliberate exposure of volunteers to pathogens to assess their response to new therapies at an early stage of development. We show here how we used public involvement to help shape the design of a CHIM to support future testing of candidate vaccines for the neglected tropical disease cutaneous leishmaniasis, a disease transmitted by the bite of infected sand flies in tropical regions. METHODS We undertook a public involvement (PI) consultation exercise to inform development of a study to test the safety and effectiveness of a sand fly biting protocol using uninfected sand flies (FLYBITE: ClinicalTrials.gov ID NCT03999970 ) and a CHIM using Leishmania major-infected sand flies (LEISH_Challenge: ClinicalTrials.gov ID NCT04512742 ), both taking place in York, UK. We involved 10 members of the public including a patient research ambassador and a previous CHIM volunteer. The session took place at The University of York, UK and examined draft study volunteer-facing material and included the CHIM study design, potential adverse events and therapeutic interventions at study endpoints. A discussion of the scientific, ethical, humanitarian and economic basis for the project was presented to the participants to provoke discourse. An inductive, thematic analysis was used to identify the participants' key concerns. RESULTS Themes were identified relating to i) quality of volunteer-facing written information, ii) improving study design, and iii) factors to motivate involvement in the research. Group participants responded positively to the overall study aims. Initial concerns were expressed about potential risks of study involvement, but further explanation of the science and mitigations of risk secured participant support. Participants provided advice and identified improved terminology to inform the volunteer-facing material. Lastly, treatment options were discussed, and excision of any cutaneous lesion was favoured over alternatives as a treatment. CONCLUSION The consultation exercise provided invaluable information which led to improved study design and enhanced clarity in the volunteer-facing material. The session also reinforced the need to maintain public trust in scientific rigour prior to initiation of any study. The investigators hope that this description strengthens understanding of PI in clinical research, and encourages its use within other studies.
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Affiliation(s)
- Vivak Parkash
- York Biomedical Research Institute, Hull York Medical School, University of York, York, UK.
- Department of Infection and Tropical Medicine, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK.
| | - Georgina Jones
- School of Social Sciences, Leeds Beckett University, Leeds, UK
| | - Nina Martin
- School of Social Sciences, Leeds Beckett University, Leeds, UK
| | | | - Elizabeth Greensted
- York Biomedical Research Institute, Hull York Medical School, University of York, York, UK
| | - Paul Kaye
- York Biomedical Research Institute, Hull York Medical School, University of York, York, UK
| | - Alison M Layton
- York Biomedical Research Institute, Hull York Medical School, University of York, York, UK
| | - Charles J Lacey
- York Biomedical Research Institute, Hull York Medical School, University of York, York, UK
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28
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Opportunities and Challenges in Developing a Cryptosporidium Controlled Human Infection Model for Testing Antiparasitic Agents. ACS Infect Dis 2021; 7:959-968. [PMID: 33822577 PMCID: PMC8154424 DOI: 10.1021/acsinfecdis.1c00057] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cryptosporidiosis is a leading cause of moderate-to-severe diarrhea in low- and middle-income countries, responsible for high mortality in children younger than two years of age, and it is also strongly associated with childhood malnutrition and growth stunting. There is no vaccine for cryptosporidiosis and existing therapeutic options are suboptimal to prevent morbidity and mortality in young children. Recently, novel therapeutic agents have been discovered through high-throughput phenotypic and target-based screening strategies, repurposing malaria hits, etc., and these agents have a promising preclinical in vitro and in vivo anti-Cryptosporidium efficacy. One key step in bringing safe and effective new therapies to young vulnerable children is the establishment of some prospect of direct benefit before initiating pediatric clinical studies. A Cryptosporidium controlled human infection model (CHIM) in healthy adult volunteers can be a robust clinical proof of concept model for evaluating novel therapeutics. CHIM could potentially accelerate the development path to pediatric studies by establishing the safety of a proposed pediatric dosing regimen and documenting preliminary efficacy in adults. We present, here, perspectives regarding the opportunities and perceived challenges with the Cryptosporidium human challenge model.
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29
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McDonald I, Murray SM, Reynolds CJ, Altmann DM, Boyton RJ. Comparative systematic review and meta-analysis of reactogenicity, immunogenicity and efficacy of vaccines against SARS-CoV-2. NPJ Vaccines 2021; 6:74. [PMID: 33986272 PMCID: PMC8116645 DOI: 10.1038/s41541-021-00336-1] [Citation(s) in RCA: 164] [Impact Index Per Article: 54.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 04/15/2021] [Indexed: 02/03/2023] Open
Abstract
As SARS-CoV-2 vaccines are deployed worldwide, a comparative evaluation is important to underpin decision-making. We here report a systematic literature review and meta-analysis of Phase I/II/III human trials and non-human primates (NHP) studies, comparing reactogenicity, immunogenicity and efficacy across different vaccine platforms for comparative evaluation (updated to March 22, 2021). Twenty-three NHP and 32 human studies are included. Vaccines result in mostly mild, self-limiting adverse events. Highest spike neutralizing antibody (nAb) responses are identified for the mRNA-1273-SARS-CoV and adjuvanted NVX-CoV2373-SARS-CoV-2 vaccines. ChAdOx-SARS-CoV-2 produces the highest T cell ELISpot responses. Pre-existing nAb against vaccine viral vector are identified following AdH-5-SARS-CoV-2 vaccination, halving immunogenicity. The mRNA vaccines depend on boosting to achieve optimal immunogenicity especially in the elderly. BNT162b2, and mRNA-1273 achieve >94%, rAd26/5 > 91% and ChAdOx-SARS-CoV-2 > 66.7% efficacy. Across different vaccine platforms there are trade-offs between antibody binding, functional nAb titers, T cell frequency, reactogenicity and efficacy. Emergence of variants makes rapid mass rollout of high efficacy vaccines essential to reduce any selective advantage.
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Affiliation(s)
- Ian McDonald
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK
| | - Sam M Murray
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK
| | - Catherine J Reynolds
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK
| | - Daniel M Altmann
- Department of Immunology and Inflammation, Faculty of Medicine, Imperial College London, London, UK.
| | - Rosemary J Boyton
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK.
- Lung Division, Royal Brompton and Harefield Hospitals, London, UK.
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30
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van Hoffen E, Mercenier A, Vidal K, Benyacoub J, Schloesser J, Kardinaal A, Lucas-van de Bos E, van Alen I, Roggero I, Duintjer K, Berendts A, Albers R, Kleerebezem M, Ten Bruggencate S. Characterization of the pathophysiological determinants of diarrheagenic Escherichia coli infection using a challenge model in healthy adults. Sci Rep 2021; 11:6060. [PMID: 33723346 PMCID: PMC7960709 DOI: 10.1038/s41598-021-85161-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 02/15/2021] [Indexed: 11/09/2022] Open
Abstract
An experimental human challenge model with an attenuated diarrheagenic Escherichia coli (E. coli) strain has been used in food intervention studies aimed to increase resistance to E. coli infection. This study was designed to refine and expand this challenge model. In a double-blind study, healthy male subjects were orally challenged with 1E10 or 5E10 colony-forming units (CFU) of E. coli strain E1392/75-2A. Three weeks later, subjects were rechallenged with 1E10 CFU of E. coli. Before and after both challenges, clinical symptoms and infection- and immune-related biomarkers were analyzed. Subset analysis was performed on clinically high- and low-responders. Regardless of inoculation dose, the first challenge induced clinical symptoms for 2-3 days. In blood, neutrophils, CRP, CXCL10, and CFA/II-specific IgG were induced, and in feces calprotectin and CFA/II-specific IgA. Despite clinical differences between high- and low-responders, infection and immune biomarkers did not differ. The first inoculation induced protection at the second challenge, with a minor clinical response, and no change in biomarkers. The refined study design resulted in a larger dynamic range of symptoms, and identification of biomarkers induced by a challenge with the attenuated E. coli strain E1392/75-2A, which is of value for future intervention studies. Addition of a second inoculation allows to study the protective response induced by a primary infection.Clinicaltrials.gov registration: NCT02541695 (04/09/2015).
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Affiliation(s)
- Els van Hoffen
- Department of Nutrition and Health, NIZO, PO Box 20, 6710 BA, Ede, the Netherlands
| | - Annick Mercenier
- Nestlé Institute of Health Sciences, Gastrointestinal Health, Nestlé Research, Lausanne, Switzerland.,NutriLeads, Wageningen, The Netherlands
| | - Karine Vidal
- Nestlé Institute of Health Sciences, Gastrointestinal Health, Nestlé Research, Lausanne, Switzerland
| | - Jalil Benyacoub
- Nestlé Institute of Health Sciences, Gastrointestinal Health, Nestlé Research, Lausanne, Switzerland
| | - Joyce Schloesser
- Department of Nutrition and Health, NIZO, PO Box 20, 6710 BA, Ede, the Netherlands.
| | - Alwine Kardinaal
- Department of Nutrition and Health, NIZO, PO Box 20, 6710 BA, Ede, the Netherlands
| | | | - Ingrid van Alen
- Department of Nutrition and Health, NIZO, PO Box 20, 6710 BA, Ede, the Netherlands
| | - Iris Roggero
- Nestlé Institute of Health Sciences, Gastrointestinal Health, Nestlé Research, Lausanne, Switzerland
| | - Kim Duintjer
- Department of Nutrition and Health, NIZO, PO Box 20, 6710 BA, Ede, the Netherlands.,Host Microbe Interactomics Group, Department of Animal Sciences, Wageningen University and Research, Wageningen, the Netherlands
| | - Anneke Berendts
- Department of Nutrition and Health, NIZO, PO Box 20, 6710 BA, Ede, the Netherlands
| | | | - Michiel Kleerebezem
- Host Microbe Interactomics Group, Department of Animal Sciences, Wageningen University and Research, Wageningen, the Netherlands
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31
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Driciru E, Koopman JPR, Cose S, Siddiqui AA, Yazdanbakhsh M, Elliott AM, Roestenberg M. Immunological Considerations for Schistosoma Vaccine Development: Transitioning to Endemic Settings. Front Immunol 2021; 12:635985. [PMID: 33746974 PMCID: PMC7970007 DOI: 10.3389/fimmu.2021.635985] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/11/2021] [Indexed: 12/16/2022] Open
Abstract
Despite mass drug administration programmes with praziquantel, the prevalence of schistosomiasis remains high. A vaccine is urgently needed to control transmission of this debilitating disease. As some promising schistosomiasis vaccine candidates are moving through pre-clinical and clinical testing, we review the immunological challenges that these vaccine candidates may encounter in transitioning through the clinical trial phases in endemic settings. Prior exposure of the target population to schistosomes and other infections may impact vaccine response and efficacy and therefore requires considerable attention. Schistosomes are known for their potential to induce T-reg/IL-10 mediated immune suppression in populations which are chronically infected. Moreover, endemicity of schistosomiasis is focal whereby target and trial populations may exhibit several degrees of prior exposure as well as in utero exposure which may increase heterogeneity of vaccine responses. The age dependent distribution of exposure and development of acquired immunity, and general differences in the baseline immunological profile, adds to the complexity of selecting suitable trial populations. Similarly, prior or concurrent infections with other parasitic helminths, viral and bacterial infections, may alter immunological responses. Consequently, treatment of co-infections may benefit the immunogenicity of vaccines and may be considered despite logistical challenges. On the other hand, viral infections leave a life-long immunological imprint on the human host. Screening for serostatus may be needed to facilitate interpretation of vaccine responses. Co-delivery of schistosome vaccines with PZQ is attractive from a perspective of implementation but may complicate the immunogenicity of schistosomiasis vaccines. Several studies have reported PZQ treatment to induce both transient and long-term immuno-modulatory effects as a result of tegument destruction, worm killing and subsequent exposure of worm antigens to the host immune system. These in turn may augment or antagonize vaccine immunogenicity. Understanding the complex immunological interactions between vaccine, co-infections or prior exposure is essential in early stages of clinical development to facilitate phase 3 clinical trial design and implementation policies. Besides well-designed studies in different target populations using schistosome candidate vaccines or other vaccines as models, controlled human infections could also help identify markers of immune protection in populations with different disease and immunological backgrounds.
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Affiliation(s)
- Emmanuella Driciru
- Immunomodulation and Vaccines Programme, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | | | - Stephen Cose
- Immunomodulation and Vaccines Programme, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Afzal A. Siddiqui
- Center for Tropical Medicine and Infectious Diseases, Texas Tech University School of Medicine, Lubbock, TX, United States
- Department of Internal Medicine, Center for Tropical Medicine and Infectious Diseases, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Maria Yazdanbakhsh
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
| | - Alison M. Elliott
- Immunomodulation and Vaccines Programme, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Meta Roestenberg
- Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands
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Topham DJ, DeDiego ML, Nogales A, Sangster MY, Sant A. Immunity to Influenza Infection in Humans. Cold Spring Harb Perspect Med 2021; 11:a038729. [PMID: 31871226 PMCID: PMC7919402 DOI: 10.1101/cshperspect.a038729] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review discusses the human immune responses to influenza infection with some insights from studies using animal models, such as experimental infection of mice. Recent technological advances in the study of human immune responses have greatly added to our knowledge of the infection and immune responses, and therefore much of the focus is on recent studies that have moved the field forward. We consider the complexity of the adaptive response generated by many sequential encounters through infection and vaccination.
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Affiliation(s)
- David J Topham
- David H. Smith Center for Vaccine Biology and Immunology, Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642, USA
| | - Marta L DeDiego
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Cientificas, 28049 Madrid, Spain
| | - Aitor Nogales
- Instituto Nacional de Investigación y Tecnologia Agraria y Ailmentaria, 28040 Madrid, Spain
| | - Mark Y Sangster
- David H. Smith Center for Vaccine Biology and Immunology, Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642, USA
| | - Andrea Sant
- David H. Smith Center for Vaccine Biology and Immunology, Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York 14642, USA
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Nguyen LC, Bakerlee CW, McKelvey TG, Rose SM, Norman AJ, Joseph N, Manheim D, McLaren MR, Jiang S, Barnes CF, Kinniment M, Foster D, Darton TC, Morrison J. Evaluating Use Cases for Human Challenge Trials in Accelerating SARS-CoV-2 Vaccine Development. Clin Infect Dis 2021; 72:710-715. [PMID: 32628748 PMCID: PMC7454474 DOI: 10.1093/cid/ciaa935] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/02/2020] [Indexed: 01/07/2023] Open
Abstract
Human challenge trials (HCTs) have been proposed as a means to accelerate SARS-CoV-2 vaccine development. We identify and discuss three potential use cases of HCTs in the current pandemic: evaluating efficacy, converging on correlates of protection, and improving understanding of pathogenesis and the human immune response. We outline the limitations of HCTs and find that HCTs are likely to be most useful for vaccine candidates currently in preclinical stages of development. We conclude that, while currently limited in their application, there are scenarios in which HCTs would be extremely beneficial. Therefore, the option of conducting HCTs to accelerate SARS-CoV-2 vaccine development should be preserved. As HCTs require many months of preparation, we recommend an immediate effort to (1) establish guidelines for HCTs for COVID-19; (2) take the first steps toward HCTs, including preparing challenge virus and making preliminary logistical arrangements; and (3) commit to periodically re-evaluating the utility of HCTs.
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Affiliation(s)
- Linh Chi Nguyen
- Department of Politics and International Relations, University of Oxford, Oxford, United Kingdom
| | - Christopher W Bakerlee
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA.,Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| | | | - Sophie M Rose
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | | | | | - David Manheim
- Health and Risk Communication Research Center, School of Public Health, University of Haifa, Haifa, Israel
| | - Michael R McLaren
- Department of Population Health and Pathobiology, North Carolina State University, Raleigh, North Carolina, USA
| | - Steven Jiang
- Harvard Law School, Cambridge, Massachusetts, USA
| | | | - Megan Kinniment
- Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Derek Foster
- Rethink Priorities, Redwood City, California, USA
| | - Thomas C Darton
- Department of Infection, Immunity, and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
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History of Human Challenge Studies. HUMAN CHALLENGE STUDIES IN ENDEMIC SETTINGS 2021. [PMCID: PMC7431914 DOI: 10.1007/978-3-030-41480-1_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The intentional infection of human beings with pathogens with the aim of achieving benefits (chiefly, the prevention of more severe disease) has occurred for centuries; the (semi-)systematic testing and recording of such methods dates to the 18th Century in England.
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Han A, Taubenberger JK, Memoli MJ. Reply to Bernstein, Atmar, and Hoft. Clin Infect Dis 2020; 71:3013-3014. [PMID: 32206777 DOI: 10.1093/cid/ciaa279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Alison Han
- LID Clinical Studies Unit, Laboratory of Infectious Diseases, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Jeffery K Taubenberger
- Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Matthew J Memoli
- LID Clinical Studies Unit, Laboratory of Infectious Diseases, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Pollard AJ, Bijker EM. A guide to vaccinology: from basic principles to new developments. Nat Rev Immunol 2020; 21:83-100. [PMID: 33353987 PMCID: PMC7754704 DOI: 10.1038/s41577-020-00479-7] [Citation(s) in RCA: 644] [Impact Index Per Article: 161.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2020] [Indexed: 12/17/2022]
Abstract
Immunization is a cornerstone of public health policy and is demonstrably highly cost-effective when used to protect child health. Although it could be argued that immunology has not thus far contributed much to vaccine development, in that most of the vaccines we use today were developed and tested empirically, it is clear that there are major challenges ahead to develop new vaccines for difficult-to-target pathogens, for which we urgently need a better understanding of protective immunity. Moreover, recognition of the huge potential and challenges for vaccines to control disease outbreaks and protect the older population, together with the availability of an array of new technologies, make it the perfect time for immunologists to be involved in designing the next generation of powerful immunogens. This Review provides an introductory overview of vaccines, immunization and related issues and thereby aims to inform a broad scientific audience about the underlying immunological concepts. This Review, aimed at a broad scientific audience, provides an introductory guide to the history, development and immunological basis of vaccines, immunization and related issues to provide insight into the challenges facing immunologists who are designing the next generation of vaccines.
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Affiliation(s)
- Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK. .,NIHR Oxford Biomedical Research Centre, Oxford University Hospitals Trust, Oxford, UK.
| | - Else M Bijker
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK.,NIHR Oxford Biomedical Research Centre, Oxford University Hospitals Trust, Oxford, UK
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Talaat KR, Porter CK, Jaep KM, Duplessis CA, Gutierrez RL, Maciel M, Adjoodani B, Feijoo B, Chakraborty S, Brubaker J, Trop SA, Riddle MS, Joseph SS, Bourgeois AL, Prouty MG. Refinement of the CS6-expressing enterotoxigenic Escherichia coli strain B7A human challenge model: A randomized trial. PLoS One 2020; 15:e0239888. [PMID: 33264302 PMCID: PMC7710093 DOI: 10.1371/journal.pone.0239888] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 09/01/2020] [Indexed: 12/29/2022] Open
Abstract
Background Human challenge models for enterotoxigenic Escherichia coli (ETEC) facilitate vaccine down-selection. The B7A (O148:H28 CS6+LT+ST+) strain is important for vaccine development. We sought to refine the B7A model by identifying a dose and fasting regimen consistently inducing moderate-severe diarrhea. Methods An initial cohort of 28 subjects was randomized (1:1:1:1) to receive B7A following an overnight fast at doses of 108 or 109 colony forming units (cfu) or a 90-minute fast at doses of 109 or 1010 cfu. A second cohort included naïve and rechallenged subjects who had moderate-severe diarrhea and were given the target regimen. Immune responses to important ETEC antigens were assessed. Results Among subjects receiving 108 cfu of B7A, overnight fast, or 109 cfu, 90-minute fast, 42.9% (3/7) had moderate-severe diarrhea. Higher attack rates (71.4%; 5/7) occurred in subjects receiving 109 cfu, overnight fast, or 1010 cfu, 90-minute fast. Upon rechallenge with 109 cfu of B7A, overnight fast, 5/11 (45.5%) had moderate-severe diarrhea; the attack rate among concurrently challenge naïve subjects was 57.9% (11/19). Anti-CS6, O148 LPS and LT responses were modest across all groups. Conclusions An overnight fast enabled a reduction in the B7A inoculum dose; however, the attack rate was inconsistent and protection upon rechallenge was minimal.
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Affiliation(s)
- Kawsar R. Talaat
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
- * E-mail:
| | - Chad K. Porter
- Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Kayla M. Jaep
- Henry M. Jackson Foundation, Bethesda, MD, United States of America
| | | | | | - Milton Maciel
- Henry M. Jackson Foundation, Bethesda, MD, United States of America
| | - Brittany Adjoodani
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Brittany Feijoo
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Jessica Brubaker
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Stefanie A. Trop
- Henry M. Jackson Foundation, Bethesda, MD, United States of America
| | - Mark S. Riddle
- Naval Medical Research Center, Silver Spring, MD, United States of America
- Uniformed Services University of the Health Sciences, Bethesda, MD, United States of America
| | | | - A. Louis Bourgeois
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
- PATH, Washington, DC, United States of America
| | - Michael G. Prouty
- Naval Medical Research Center, Silver Spring, MD, United States of America
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Grimwade O, Savulescu J, Giubilini A, Oakley J, Osowicki J, Pollard AJ, Nussberger AM. Payment in challenge studies: ethics, attitudes and a new payment for risk model. JOURNAL OF MEDICAL ETHICS 2020; 46:815-826. [PMID: 32978306 PMCID: PMC7719900 DOI: 10.1136/medethics-2020-106438] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/09/2020] [Accepted: 08/07/2020] [Indexed: 05/22/2023]
Abstract
Controlled Human Infection Model (CHIM) research involves the infection of otherwise healthy participants with disease often for the sake of vaccine development. The COVID-19 pandemic has emphasised the urgency of enhancing CHIM research capability and the importance of having clear ethical guidance for their conduct. The payment of CHIM participants is a controversial issue involving stakeholders across ethics, medicine and policymaking with allegations circulating suggesting exploitation, coercion and other violations of ethical principles. There are multiple approaches to payment: reimbursement, wage payment and unlimited payment. We introduce a new Payment for Risk Model, which involves paying for time, pain and inconvenience and for risk associated with participation. We give philosophical arguments based on utility, fairness and avoidance of exploitation to support this. We also examine a cross-section of the UK public and CHIM experts. We found that CHIM participants are currently paid variable amounts. A representative sample of the UK public believes CHIM participants should be paid approximately triple the UK minimum wage and should be paid for the risk they endure throughout participation. CHIM experts believe CHIM participants should be paid more than double the UK minimum wage but are divided on the payment for risk. The Payment for Risk Model allows risk and pain to be accounted for in payment and could be used to determine ethically justifiable payment for CHIM participants.Although many research guidelines warn against paying large amounts or paying for risk, our empirical findings provide empirical support to the growing number of ethical arguments challenging this status quo. We close by suggesting two ways (value of statistical life or consistency with risk in other employment) by which payment for risk could be calculated.
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Affiliation(s)
- Olivia Grimwade
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
- Oxford Uehiro Centre for Practical Ethics, University of Oxford, Oxford, UK
| | - Julian Savulescu
- Oxford Uehiro Centre for Practical Ethics, University of Oxford, Oxford, UK
- Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Melbourne Law School, University of Melbourne, Melbourne, Victoria, Australia
| | - Alberto Giubilini
- Oxford Uehiro Centre for Practical Ethics, University of Oxford, Oxford, UK
- Wellcome Centre for Ethics and Humanities, University of Oxford, Oxford, UK
| | - Justin Oakley
- Monash Bioethics Centre, Monash University, Melbourne, Victoria, Australia
| | - Joshua Osowicki
- Tropical Diseases Research Group, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
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Jamrozik E, Littler K, Bull S, Emerson C, Kang G, Kapulu M, Rey E, Saenz C, Shah S, Smith PG, Upshur R, Weijer C, Selgelid MJ. Key criteria for the ethical acceptability of COVID-19 human challenge studies: Report of a WHO Working Group. Vaccine 2020; 39:633-640. [PMID: 33341309 PMCID: PMC7598752 DOI: 10.1016/j.vaccine.2020.10.075] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 10/21/2020] [Indexed: 12/13/2022]
Abstract
This report of the WHO Working Group for Guidance on Human Challenge Studies in COVID-19 outlines ethical standards for COVID-19 challenge studies. It includes eight Key Criteria related to scientific justification, risk-benefit assessment, consultation and engagement, co-ordination of research, site selection, participant selection, expert review, and informed consent. The document aims to provide comprehensive guidance to scientists, research ethics committees, funders, policymakers, and regulators in deliberations regarding SARS-CoV-2 challenge studies by outlining criteria that would need to be satisfied in order for such studies to be ethically acceptable.
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Affiliation(s)
- Euzebiusz Jamrozik
- The Ethox Centre & Wellcome Centre for Ethics and the Humanities, Nuffield Department of Population Health, University of Oxford, Oxford, Oxfordshire, UK; Monash Bioethics Centre, Monash University, Clayton, Victoria, Australia; Royal Melbourne Hospital Department of Medicine, University of Melbourne, Parkville, Victoria, Australia
| | - Katherine Littler
- Global Health Ethics Unit, World Health Organization, Geneva, Switzerland
| | - Susan Bull
- The Ethox Centre & Wellcome Centre for Ethics and the Humanities, Nuffield Department of Population Health, University of Oxford, Oxford, Oxfordshire, UK
| | - Claudia Emerson
- Institute on Ethics & Policy for Innovation, Department of Philosophy, McMaster University, Hamilton, Ontario, Canada
| | - Gagandeep Kang
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Melissa Kapulu
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Elena Rey
- Centro Internacional de Entrenamiento e Investigaciones Médicas - CIDEIM. Cali, Colombia; Universidad Icesi. Cali, Colombia
| | - Carla Saenz
- Department of Health Systems and Services, Pan American Health Organization, USA
| | - Seema Shah
- Lurie Children's Hospital & Northwestern University Feinberg School of Medicine, Chicago, USA
| | - Peter G Smith
- London School of Hygiene and Tropical Medicine, London, UK
| | - Ross Upshur
- Division of Clinical Public Health, Dalla Lana School of Public Health, Toronto, Canada
| | - Charles Weijer
- Departments of Medicine, Epidemiology & Biostatistics, and Philosophy, Western University, London, Canada
| | - Michael J Selgelid
- Monash Bioethics Centre, Monash University, Clayton, Victoria, Australia
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Chilengi R, Simuyandi M, Chibuye M, Chirwa M, Sukwa N, Laban N, Chisenga C, Silwamba S, Grassly N, Bosomprah S. A pilot study on use of live attenuated rotavirus vaccine (Rotarix™) as an infection challenge model. Vaccine 2020; 38:7357-7362. [PMID: 33032844 DOI: 10.1016/j.vaccine.2020.09.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 09/05/2020] [Accepted: 09/08/2020] [Indexed: 12/24/2022]
Abstract
BACKGROUND Rotavirus remains the commonest cause of dehydrating diarrhoea, particularly in developing countries. Human infection challenge studies in children in these countries offers an opportunity to rapidly evaluate new vaccine candidates that may have improved efficacy. We evaluated use of Rotarix™ as a live-attenuated challenge agent. METHODS We undertook an open label, exploratory study in infants receiving two standard doses of Rotarix™ at 6 and 10 weeks of age in a cohort of 22 Zambian infants. The first vaccine dose was considered as primary vaccination, and the second at day 28 as a live-attenuated virus challenge. Saliva, stool and serum samples were collected on days 0, 3, 5, 7, 14, and 28 following each dose. The primary outcome was stool shedding of rotavirus, determined by NSP2 qPCR. We calculated mean shedding index as average of natural logarithm of viral copies per gram of stool. FINDINGS After the first dose, viral shedding was high at day 3, peaked by day 5. After the second dose, viral shedding at day 3 was low and reduced gradually in most infants until day 14. Mean shedding index was significantly lower post dose 2 across all infants and timepoints (5.0 virus copies/g of stool [95%CI: 0.3-9.7] vs 10.4 virus copies/g of stool [95%CI: 6.2-14.6]; p-value < 0.0001; rho = 0.20, SD = 4.97. Seroconversion at day 28 was associated with a mean reduction of -1.03 (95%CI = -8.07, 6.01) in viral shedding after challenge dose but this was not statistically significant (p = 0.774). A borderline positive correlation between fold-change in IgA titre at day 28 from day 0 in saliva and serum was observed; Spearman's correlation coefficient, r = 0.69; p = 0.086. INTERPRETATION Shedding after the 'challenge' dose was reduced compared with the first dose, consistent with the induction of mucosal immunity by the first dose. This supports the use of Rotarix vaccine as a live-attenuated infection challenge. FUNDING Medical Research Council (UK) through the HIC-Vac Network.
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Affiliation(s)
- Roma Chilengi
- Research Division, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.
| | - Michelo Simuyandi
- Research Division, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Mwelwa Chibuye
- Research Division, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Masuzyo Chirwa
- Research Division, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Nsofwa Sukwa
- Research Division, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Natasha Laban
- Research Division, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Caroline Chisenga
- Research Division, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Suwilanji Silwamba
- Research Division, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia
| | - Nicholas Grassly
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom
| | - Samuel Bosomprah
- Research Division, Centre for Infectious Disease Research in Zambia, Lusaka, Zambia; Department of Biostatistics, School of Public Health, University of Ghana, Accra, Ghana
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Wressnigg N, Hochreiter R, Zoihsl O, Fritzer A, Bézay N, Klingler A, Lingnau K, Schneider M, Lundberg U, Meinke A, Larcher-Senn J, Čorbic-Ramljak I, Eder-Lingelbach S, Dubischar K, Bender W. Single-shot live-attenuated chikungunya vaccine in healthy adults: a phase 1, randomised controlled trial. THE LANCET. INFECTIOUS DISEASES 2020; 20:1193-1203. [DOI: 10.1016/s1473-3099(20)30238-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 12/18/2019] [Accepted: 03/16/2020] [Indexed: 12/14/2022]
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Grady C, Shah S, Miller F, Danis M, Nicolini M, Ochoa J, Taylor H, Wendler D, Rid A. So much at stake: Ethical tradeoffs in accelerating SARSCoV-2 vaccine development. Vaccine 2020; 38:6381-6387. [PMID: 32826103 PMCID: PMC7418641 DOI: 10.1016/j.vaccine.2020.08.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/03/2020] [Accepted: 08/06/2020] [Indexed: 02/08/2023]
Abstract
BACKGROUND A sense of urgency exists to develop vaccines against SARS CoV-2, responsible for numerous global cases and deaths, as well as widespread social and economic disruption. Multiple approaches have been proposed to speed up vaccine development, including accelerated randomized controlled trials (RCT), controlled human challenge trials (CHI), and wide distribution through an emergency use authorization after collecting initial data. There is a need to examine how best to accelerate vaccine development in the setting of a pandemic, without compromising ethical and scientific norms. METHODS Trade-offs in scientific and social value between generating reliable evidence about safety and efficacy while promoting rapid vaccine availability are examined along five ethically relevant dimensions: (1) confidence in and generalizability of data, (2) feasibility, (3) speed and cost, (4) participant risks, and (5) social risks. RESULTS Accelerated individually randomized RCTs permit expeditious evaluation of vaccine candidates using established methods, expertise, and infrastructure. RCTs are more likely than other approaches to be feasible, increase speed and reduce cost, and generate reliable data about safety and efficacy without significantly increasing risks to participants or undermining societal trust. CONCLUSION Ethical analysis suggests that accelerated RCTs are the best approach to accelerating vaccine development in a pandemic, and more likely than other approaches to enhance social value without compromising ethics or science. RCTs can expeditiously collect rigorous data about vaccine safety and efficacy. Innovative and flexible designs and implementation strategies to respond to shifting incidence and test vaccine candidates in parallel or sequentially would add value, as will coordinated data sharing across vaccine trials. CHI studies may be an important complementary strategy when more is known. Widely disseminating a vaccine candidate without efficacy data will not serve the public health nor achieve the goal of identifying safe and effective SARS Co-V-2 vaccines.
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Affiliation(s)
- Christine Grady
- Department of Bioethics, National Institutes of Health Clinical Center, Building 10/1C118, NIH, Bethesda, MD 20892, United States.
| | - Seema Shah
- Lurie Children's Hospital, Northwestern University, Department of Pediatrics, 225 E. Chicago Ave, Chicago, IL 60611, United States.
| | - Franklin Miller
- Weill Cornell Medical College, Weill Cornell Medical College, 1300 York Ave, New York, NY 10065, United States.
| | - Marion Danis
- Department of Bioethics, National Institutes of Health Clinical Center, Building 10/1C118, NIH, Bethesda, MD 20892, United States.
| | - Marie Nicolini
- Department of Bioethics, National Institutes of Health Clinical Center, Building 10/1C118, NIH, Bethesda, MD 20892, United States.
| | - Jorge Ochoa
- Department of Bioethics, National Institutes of Health Clinical Center, Building 10/1C118, NIH, Bethesda, MD 20892, United States.
| | - Holly Taylor
- Department of Bioethics, National Institutes of Health Clinical Center, Building 10/1C118, NIH, Bethesda, MD 20892, United States.
| | - Dave Wendler
- Department of Bioethics, National Institutes of Health Clinical Center, Building 10/1C118, NIH, Bethesda, MD 20892, United States.
| | - Annette Rid
- Department of Bioethics, National Institutes of Health Clinical Center, Building 10/1C118, NIH, Bethesda, MD 20892, United States.
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Giersing BK, Porter CK, Kotloff K, Neels P, Cravioto A, MacLennan CA. How can controlled human infection models accelerate clinical development and policy pathways for vaccines against Shigella? Vaccine 2020; 37:4778-4783. [PMID: 31358238 DOI: 10.1016/j.vaccine.2019.03.036] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 03/07/2019] [Accepted: 03/19/2019] [Indexed: 11/24/2022]
Abstract
Controlled Human Infection Models (CHIMs) now exist for several infectious diseases. CHIMs offer significant insight into disease pathogenesis, as well the potential to rapidly test clinical proof-of-concept of vaccine candidates. The application of CHIMs to identify a correlate of protection that may reduce the sample size of, or obviate the need for clinical efficacy studies to achieve licensure is of considerable interest to vaccine developers and public health stakeholders. This topic was the subject of a workshop at the 2018 Vaccines Against Shigella and ETEC (VASE) conference, in the context of O-antigen-based Shigella vaccines.
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Affiliation(s)
- Birgitte K Giersing
- Initiative for Vaccine Research, Department of Immunization, Vaccines & Biologicals, World Health Organization Headquarters, 20 Avenue Appia, 1211-CH 27 Geneva, Switzerland.
| | - Chad K Porter
- Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Karen Kotloff
- Department of Pediatrics and Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Pieter Neels
- International Alliance for Biological Standardization, Geneva, Switzerland
| | - Alejandro Cravioto
- Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Calman A MacLennan
- Enteric & Diarrheal Diseases, Global Health, Bill & Melinda Gates Foundation, Seattle, WA, USA
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Jamrozik E, Selgelid MJ. Human infection challenge studies in endemic settings and/or low-income and middle-income countries: key points of ethical consensus and controversy. JOURNAL OF MEDICAL ETHICS 2020; 46:601-609. [PMID: 32381683 PMCID: PMC7476299 DOI: 10.1136/medethics-2019-106001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/26/2020] [Accepted: 03/11/2020] [Indexed: 05/04/2023]
Abstract
Human infection challenge studies (HCS) involve intentionally infecting research participants with pathogens (or other micro-organisms). There have been recent calls for more HCS to be conducted in low-income and middle-income countries (LMICs), where many relevant diseases are endemic. HCS in general, and HCS in LMICs in particular, raise numerous ethical issues. This paper summarises the findings of a project that explored ethical and regulatory issues related to LMIC HCS via (i) a review of relevant literature and (ii) 45 qualitative interviews with scientists and ethicists. Among other areas of consensus, we found that there was widespread agreement that LMIC HCS can be ethically acceptable, provided that they have a sound scientific rationale, are accepted by local communities and meet usual research ethics requirements. Unresolved issues include those related to (i) acceptable approaches to trade-offs between the scientific aim to produce generalisable results and the protection of participants, (iii) the sharing of benefits with LMIC populations, (iii) the acceptable limits to risks and burdens for participants, (iv) the potential for third-party risk and whether the degree of acceptable third-party risk is different in endemic settings, (v) the conditions under which (if any) it would be appropriate to recruit children for disease-causing HCS, (v) appropriate levels of payment to participants and (vi) appropriate governance of (LMIC) HCS. This paper provides preliminary analyses of these ethical considerations in order to (i) inform scientists and policymakers involved in the planning, conduct and/or governance of LMIC HCS and (ii) highlight areas warranting future research. Insofar as this article focuses on HCS in (endemic) settings where diseases are present and/or widespread, much of the analysis provided is relevant to HCS (in HICs or LMICs) involving pandemic diseases including COVID19.
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Affiliation(s)
- Euzebiusz Jamrozik
- Monash Bioethics Centre, Monash University, Melbourne, Victoria, Australia
- Department of General Medicine, Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Michael J Selgelid
- Monash Bioethics Centre, Monash University, Melbourne, Victoria, Australia
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Liu S, Piao X, Hou N, Cai P, Ma Y, Chen Q. Duplex real-time PCR for sexing Schistosoma japonicum cercariae based on W chromosome-specific genes and its applications. PLoS Negl Trop Dis 2020; 14:e0008609. [PMID: 32822351 PMCID: PMC7467314 DOI: 10.1371/journal.pntd.0008609] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 09/02/2020] [Accepted: 07/15/2020] [Indexed: 02/07/2023] Open
Abstract
As a unique feature among otherwise hermaphroditic trematodes, Schistosoma species are gonochoric parasites whose sex is genetically determined (ZZ for males and ZW for females). However, schistosome larvae are morphologically identical, and sex can only be discriminated by molecular methods. Here, we integrated published Schistosoma. japonicum transcriptome and genome data to identify W chromosome-specific genes as sex biomarkers. Three W chromosome-specific genes of S. japonicum were identified as sex biomarkers from a panel of 12 genes expressed only in females. An efficient duplex real-time PCR (qPCR) method for sexing cercariae was developed which could identify the sex of cercariae within 2 h without DNA extraction. Moreover, this method can be used to identify not only single-sex but also mixed-sex schistosome-infected snails. We observed a nearly equal proportion of single-male, single-female, and mixed-sex schistosome infections in artificially infected snails. Sex-known schistosome-infected snail models can be efficiently constructed with the aid of duplex qPCR. A field study revealed that single-sex schistosome infections were predominant among naturally infected snails. Finally, a schistosomiasis mouse model based on sex-known cercariae infection was shown to be more reliable than a model based on sex-unknown cercariae infection. The developed duplex qPCR method for sexing S. japonicum cercariae can be widely used for schistosomiasis modeling, genetic experiments, and field-based molecular epidemiological studies. Schistosoma japonicum is a major causative agent of human schistosomiasis. Unlike other parasitic worms, S. japonicum females are determined by the heterogametic sex chromosome (ZW) and males by the homogametic sex chromosome (ZZ). The life cycle of S. japonicum includes the egg, miracidium, mother sporocyst, daughter sporocyst, cercaria, schistosomulum, and adult stages. The sex of adult male and female worms can be morphologically distinguished, whereas the sex of larvae, such as cercariae, can only be discriminated by molecular methods. In this study, we established an efficient duplex real-time PCR method for sexing S. japonicum cercariae based on newly identified W chromosome-specific genes. The established duplex real-time PCR method will facilitate construction of sex-controlled schistosome-infected intermediate host or definitive host models for schistosome-host interplays and schistosomiasis studies. This method is also a powerful tool for investigating the epidemiology of single-sex and mixed-sex schistosome-infected snails in the field.
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Affiliation(s)
- Shuai Liu
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China
- * E-mail: (SL); (QC)
| | - Xianyu Piao
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China
| | - Nan Hou
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China
| | - Pengfei Cai
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Yu Ma
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China
| | - Qijun Chen
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China
- Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agriculture University, Shenyang, P.R. China
- * E-mail: (SL); (QC)
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46
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Jamrozik E, Selgelid MJ. COVID-19 human challenge studies: ethical issues. THE LANCET. INFECTIOUS DISEASES 2020; 20:e198-e203. [PMID: 32479747 PMCID: PMC7259898 DOI: 10.1016/s1473-3099(20)30438-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/21/2020] [Accepted: 04/29/2020] [Indexed: 12/20/2022]
Abstract
COVID-19 poses an extraordinary threat to global public health and an effective vaccine could provide a key means of overcoming this crisis. Human challenge studies involve the intentional infection of research participants and can accelerate or improve vaccine development by rapidly providing estimates of vaccine safety and efficacy. Human challenge studies of low virulence coronaviruses have been done in the past and human challenge studies with severe acute respiratory syndrome coronavirus 2 have been proposed. These studies of coronaviruses could provide considerable benefits to public health; for instance, by improving and accelerating vaccine development. However, human challenge studies of severe acute respiratory syndrome coronavirus 2 in particular might be controversial, in part, for ethical reasons. The ethical issues raised by such studies thus warrant early consideration involving, for example, broad consultation with the community. This Personal View provides preliminary analyses of relevant ethical considerations regarding human challenge studies of severe acute respiratory syndrome coronavirus 2, including the potential benefits to public health and to participants, the risks and uncertainty for participants, and the third-party risks (ie, to research staff and the wider community). We argue that these human challenge studies can reasonably be considered ethically acceptable insofar as such studies are accepted internationally and by the communities in which they are done, can realistically be expected to accelerate or improve vaccine development, have considerable potential to directly benefit participants, are designed to limit and minimise risks to participants, and are done with strict infection control measures to limit and reduce third-party risks.
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Affiliation(s)
- Euzebiusz Jamrozik
- Monash Bioethics Centre and WHO Collaborating Centre for Bioethics, Monash University, Melbourne, VIC, Australia; Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, VIC, Australia.
| | - Michael J Selgelid
- Monash Bioethics Centre and WHO Collaborating Centre for Bioethics, Monash University, Melbourne, VIC, Australia
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Abstract
The increasing recent interest in human challenge studies or controlled human infection model studies for accelerating vaccine development has been driven by the recognition of the unique ability of these studies to contribute to the understanding of response to infection and the performance of vaccines. With streamlining of ethical processes, conduct and supervision and the availability of new investigative tools from immunophenotyping to glycobiology, the potential to derive valuable data to inform vaccine testing and development has never been greater. However, issues of availability and standardization of challenge strains, conduct of studies in disease endemic locations and the iteration between clinical and laboratory studies still need to be addressed to gain maximal value for vaccine development.
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Affiliation(s)
- Amrita Sekhar
- Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Gagandeep Kang
- Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India.
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Hoogerwerf MA, de Vries M, Roestenberg M. Money-oriented risk-takers or deliberate decision-makers: a cross-sectional survey study of participants in controlled human infection trials. BMJ Open 2020; 10:e033796. [PMID: 32713843 PMCID: PMC7383945 DOI: 10.1136/bmjopen-2019-033796] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE To quantitatively investigate the motivations, decision-making and experience of participants in controlled human infection (CHI) studies. DESIGN Cross-sectional descriptive survey study. SETTING Previous participants of CHI studies at the Leiden Controlled Human Infection Center, control group of students from Leiden University. PARTICIPANTS 61 previous participants and 156 controls. MEASUREMENTS Ranking of motivational and decisional factors, risk propensity score and multiple-choice questions on experience of trial participation and ethical aspects of CHI studies. RESULTS Motivating factors for participants were contributing to science (81%), contributing to research that may benefit developing countries (72%) and the financial compensation (63%). For 51% of participants, a reason other than financial compensation was the most important motivational factor. Participants considered trust in the study team (70%), time investment (63%), severity of symptoms (54%), chance of developing symptoms (54%) and whether it is an easy way to make money (54%) in their decision to participate. Most CHI participants (84%) were proud of their participation, would advise others to participate (89%) and would participate in a similar trial again (85%). CHI participants had a higher risk propensity score than students (estimated difference 0.9, p<0.001). CONCLUSION Although financial compensation is important, the motivations for participants in a CHI study are diverse and participants make a balanced appraisal of risks and burden before participating.
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Affiliation(s)
| | - Martine de Vries
- Medical Ethics and Health Law, Leiden University Medical Center, Leiden, Zuid-Holland, The Netherlands
| | - Meta Roestenberg
- Parasitology, Leiden University Medical Center, Leiden, Zuid-Holland, The Netherlands
- Infectious Diseases, Leiden University Medical Center, Leiden, Zuid-Holland, The Netherlands
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49
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Hoogerwerf MA, Koopman JPR, Janse JJ, Langenberg MCC, van Schuijlenburg R, Kruize YCM, Brienen EAT, Manurung MD, Verbeek-Menken P, van der Beek MT, Westra IM, Meij P, Visser LG, van Lieshout L, de Vlas SJ, Yazdanbakhsh M, Coffeng LE, Roestenberg M. A Randomized Controlled Trial to Investigate Safety and Variability of Egg Excretion After Repeated Controlled Human Hookworm Infection. J Infect Dis 2020; 223:905-913. [PMID: 32645714 DOI: 10.1093/infdis/jiaa414] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 07/09/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Controlled human hookworm infections could significantly contribute to the development of a hookworm vaccine. However, current models are hampered by low and unstable egg output, reducing generalizability and increasing sample sizes. This study aims to investigate the safety, tolerability, and egg output of repeated exposure to hookworm larvae. METHODS Twenty-four healthy volunteers were randomized, double-blindly, to 1, 2, or 3 doses of 50 Necator americanus L3 larvae at 2-week intervals. Volunteers were monitored weekly and were treated with albendazole at week 20. RESULTS There was no association between larval dose and number or severity of adverse events. Geometric mean egg loads stabilized at 697, 1668, and 1914 eggs per gram feces for the 1 × 50L3, 2 × 50L3, and 3 × 50L3 group, respectively. Bayesian statistical modeling showed that egg count variability relative to the mean was reduced with a second infectious dose; however, the third dose did not increase egg load or decrease variability. We therefore suggest 2 × 50L3 as an improved challenge dose. Model-based simulations indicates increased frequency of stool sampling optimizes the power of hypothetical vaccine trials. CONCLUSIONS Repeated infection with hookworm larvae increased egg counts to levels comparable to the field and reduced relative variability in egg output without aggravating adverse events. CLINICAL TRIALS REGISTRATION NCT03257072.
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Affiliation(s)
| | - Jan Pieter R Koopman
- Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands
| | - Jacqueline J Janse
- Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands
| | | | | | - Yvonne C M Kruize
- Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands
| | - Eric A T Brienen
- Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands
| | - Mikhael D Manurung
- Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands
| | - Petra Verbeek-Menken
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, the Netherlands
| | - Martha T van der Beek
- Clinical Microbiology Laboratory, Leiden University Medical Center, Leiden, the Netherlands
| | - Inge M Westra
- Department of Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, the Netherlands
| | - Pauline Meij
- Department of Clinical Pharmacy & Toxicology, Leiden University Medical Center, Leiden, the Netherlands
| | - Leo G Visser
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, the Netherlands
| | - Lisette van Lieshout
- Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands
| | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Maria Yazdanbakhsh
- Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands
| | - Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Meta Roestenberg
- Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands.,Department of Infectious Diseases, Leiden University Medical Center, Leiden, the Netherlands
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50
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Bekeredjian-Ding I, Van Molle W, Baay M, Neels P. Human challenge trial workshop: Focus on quality requirements for challenge agents, Langen, Germany, October 22, 2019. Biologicals 2020; 66:53-61. [PMID: 32389512 DOI: 10.1016/j.biologicals.2020.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 04/29/2020] [Indexed: 01/01/2023] Open
Abstract
Controlled human infection models can be helpful to study pathogenesis and immune responses as a basis for the development of vaccines. In controlled human infection models, human challenge agents are used to infect healthy volunteers, therefore, ethical considerations include that the exposure studies need to be safe and results should be meaningful, e.g. contribute to a better cure. Both in the US and in Europe, the level of Good Manufacturing Practice required is related to the phase of the study ('sliding scale Good Manufacturing Practice'), and, hence, is much more open to speedy drug development than anticipated. Recommendations included: the development of guidelines for human challenge agents; a focus on strain selection, in particular with regard to strain infectivity, stability and purity; the use of whole genome sequencing; a reference repository of challenge agents, the need for early exchange with regulators to ensure acceptability of strain selection and manufacturing for later drug development; sharing of models and challenge agents.
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Affiliation(s)
- Isabelle Bekeredjian-Ding
- Paul-Ehrlich-Institut (PEI), Langen, Germany; Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany.
| | | | - Marc Baay
- P95 Epidemiology & Pharmacovigilance, Leuven, Belgium.
| | - Pieter Neels
- International Alliance for Biological Standardization (IABS), Belgium.
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