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Snider CJ, Zaman K, Wilkinson AL, Binte Aziz A, Yunus M, Haque W, Jones KAV, Wei L, Estivariz CF, Konopka-Anstadt JL, Mainou BA, Patel JC, Lickness JS, Pallansch MA, Wassilak SGF, Steven Oberste M, Anand A. Poliovirus type 1 systemic humoral and intestinal mucosal immunity induced by monovalent oral poliovirus vaccine, fractional inactivated poliovirus vaccine, and bivalent oral poliovirus vaccine: A randomized controlled trial. Vaccine 2023; 41:6083-6092. [PMID: 37652822 PMCID: PMC10895964 DOI: 10.1016/j.vaccine.2023.08.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/10/2023] [Accepted: 08/22/2023] [Indexed: 09/02/2023]
Abstract
BACKGROUND To inform response strategies, we examined type 1 humoral and intestinal immunity induced by 1) one fractional inactivated poliovirus vaccine (fIPV) dose given with monovalent oral poliovirus vaccine (mOPV1), and 2) mOPV1 versus bivalent OPV (bOPV). METHODS We conducted a randomized, controlled, open-label trial in Dhaka, Bangladesh. Healthy infants aged 5 weeks were block randomized to one of four arms: mOPV1 at age 6-10-14 weeks/fIPV at 6 weeks (A); mOPV1 at 6-10-14 weeks/fIPV at 10 weeks (B); mOPV1 at 6-10-14 weeks (C); and bOPV at 6-10-14 weeks (D). Immune response at 10 weeks and cumulative response at 14 weeks was assessed among the modified intention-to-treat population, defined as seroconversion from seronegative (<1:8 titers) to seropositive (≥1:8) or a four-fold titer rise among seropositive participants sustained to age 18 weeks. We examined virus shedding after two doses of mOPV1 with and without fIPV, and after the first mOPV1 or bOPV dose. The trial is registered at ClinicalTrials.gov (NCT03722004). FINDINGS During 18 December 2018 - 23 November 2019, 1,192 infants were enrolled (arms A:301; B:295; C:298; D:298). Immune responses at 14 weeks did not differ after two mOPV1 doses alone (94% [95% CI: 91-97%]) versus two mOPV1 doses with fIPV at 6 weeks (96% [93-98%]) or 10 weeks (96% [93-98%]). Participants who received mOPV1 and fIPV at 10 weeks had significantly lower shedding (p < 0·001) one- and two-weeks later compared with mOPV1 alone. Response to one mOPV1 dose was significantly higher than one bOPV dose (79% versus 67%; p < 0·001) and shedding two-weeks later was significantly higher after mOPV1 (76% versus 56%; p < 0·001) indicating improved vaccine replication. Ninety-nine adverse events were reported, 29 serious including two deaths; none were attributed to study vaccines. INTERPRETATION Given with the second mOPV1 dose, fIPV improved intestinal immunity but not humoral immunity. One mOPV1 dose induced higher humoral and intestinal immunity than bOPV. FUNDING U.S. Centers for Disease Control and Prevention.
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Affiliation(s)
- Cynthia J Snider
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
| | - Khalequ Zaman
- icddr,b, 68 Shahid Tajuddin Ahmed Sarani, Dhaka 1212, Bangladesh
| | - Amanda L Wilkinson
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA.
| | - Asma Binte Aziz
- icddr,b, 68 Shahid Tajuddin Ahmed Sarani, Dhaka 1212, Bangladesh
| | - Mohammad Yunus
- icddr,b, 68 Shahid Tajuddin Ahmed Sarani, Dhaka 1212, Bangladesh
| | - Warda Haque
- icddr,b, 68 Shahid Tajuddin Ahmed Sarani, Dhaka 1212, Bangladesh
| | - Kathryn A V Jones
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
| | - Ling Wei
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
| | - Concepcion F Estivariz
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
| | | | - Bernardo A Mainou
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
| | - Jaymin C Patel
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
| | - Jacquelyn S Lickness
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
| | - Mark A Pallansch
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
| | - Steven G F Wassilak
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
| | - M Steven Oberste
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
| | - Abhijeet Anand
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road Northeast, Atlanta, GA 30329, USA
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Transparent reporting of recruitment and informed consent approaches in clinical trials recruiting children with minor parents in sub-Saharan Africa: a secondary analysis based on a systematic review. BMC Public Health 2021; 21:1473. [PMID: 34320934 PMCID: PMC8318049 DOI: 10.1186/s12889-021-11079-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 05/18/2021] [Indexed: 11/24/2022] Open
Abstract
Background Standardised checklists of items to be addressed in clinical study protocols and publications are promoting transparency in research. However, particular specifications for exceptional cases, such as children with minor parents are missing. This study aimed to examine the level of transparency regarding recruitment and informed consent approaches in publications of clinical trials recruiting children with minor parents in sub-Saharan Africa. We thereby focused particularly on the transparency about consenting persons (i.e. proxy decision-makers) and assessed the need to expand reporting guidelines for such exceptional cases. Methods We conducted a secondary analysis of clinical trial publications previously identified through a systematic review. Multiple scientific databases were searched up to March 2019. Clinical trial publications addressing consent and potentially recruiting children with minor parents in sub-Saharan Africa were included. 44 of the in total 4382 screened articles met our inclusion criteria. A descriptive analysis was performed. Results None of the included articles provided full evidence on whether any recruited children had minor parents and how consent was obtained for them. Four proxy decision-maker types were identified (parents; parents or guardians; guardians; or caregivers), with further descriptions provided rarely and mostly in referenced clinical trial registrations or protocols. Also, terminology describing proxy decision-makers was often used inconsistently. Conclusions Reporting the minimum maternal age alongside maternal data provided in baseline demographics can increase transparency on the recruitment of children with minor mothers. The CONSORT checklist should require clinical trial publications to state or reference exceptional informed consent procedures applied for special population groups. A standardized definition of proxy decision-maker types in international clinical trial guidelines would facilitate correct and transparent informed consent for children and children with minor parents. Study registration CRD42018074220. Supplementary Information The online version contains supplementary material available at 10.1186/s12889-021-11079-y.
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Pons-Salort M, Molodecky NA, O’Reilly KM, Wadood MZ, Safdar RM, Etsano A, Vaz RG, Jafari H, Grassly NC, Blake IM. Population Immunity against Serotype-2 Poliomyelitis Leading up to the Global Withdrawal of the Oral Poliovirus Vaccine: Spatio-temporal Modelling of Surveillance Data. PLoS Med 2016; 13:e1002140. [PMID: 27701425 PMCID: PMC5049753 DOI: 10.1371/journal.pmed.1002140] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 08/26/2016] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Global withdrawal of serotype-2 oral poliovirus vaccine (OPV2) took place in April 2016. This marked a milestone in global polio eradication and was a public health intervention of unprecedented scale, affecting 155 countries. Achieving high levels of serotype-2 population immunity before OPV2 withdrawal was critical to avoid subsequent outbreaks of serotype-2 vaccine-derived polioviruses (VDPV2s). METHODS AND FINDINGS In August 2015, we estimated vaccine-induced population immunity against serotype-2 poliomyelitis for 1 January 2004-30 June 2015 and produced forecasts for April 2016 by district in Nigeria and Pakistan. Population immunity was estimated from the vaccination histories of children <36 mo old identified with non-polio acute flaccid paralysis (AFP) reported through polio surveillance, information on immunisation activities with different oral poliovirus vaccine (OPV) formulations, and serotype-specific estimates of the efficacy of these OPVs against poliomyelitis. District immunity estimates were spatio-temporally smoothed using a Bayesian hierarchical framework. Coverage estimates for immunisation activities were also obtained, allowing for heterogeneity within and among districts. Forward projections of immunity, based on these estimates and planned immunisation activities, were produced through to April 2016 using a cohort model. Estimated population immunity was negatively correlated with the probability of VDPV2 poliomyelitis being reported in a district. In Nigeria and Pakistan, declines in immunity during 2008-2009 and 2012-2013, respectively, were associated with outbreaks of VDPV2. Immunity has since improved in both countries as a result of increased use of trivalent OPV, and projections generally indicated sustained or improved immunity in April 2016, such that the majority of districts (99% [95% uncertainty interval 97%-100%] in Nigeria and 84% [95% uncertainty interval 77%-91%] in Pakistan) had >70% population immunity among children <36 mo old. Districts with lower immunity were clustered in northeastern Nigeria and northwestern Pakistan. The accuracy of immunity estimates was limited by the small numbers of non-polio AFP cases in some districts, which was reflected by large uncertainty intervals. Forecasted improvements in immunity for April 2016 were robust to the uncertainty in estimates of baseline immunity (January-June 2015), vaccine coverage, and vaccine efficacy. CONCLUSIONS Immunity against serotype-2 poliomyelitis was forecasted to improve in April 2016 compared to the first half of 2015 in Nigeria and Pakistan. These analyses informed the endorsement of OPV2 withdrawal in April 2016 by the WHO Strategic Advisory Group of Experts on Immunization.
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Affiliation(s)
- Margarita Pons-Salort
- Department of Infectious Disease Epidemiology, St Mary’s Campus, Imperial College London, London, United Kingdom
| | - Natalie A. Molodecky
- Department of Infectious Disease Epidemiology, St Mary’s Campus, Imperial College London, London, United Kingdom
| | - Kathleen M. O’Reilly
- Department of Infectious Disease Epidemiology, St Mary’s Campus, Imperial College London, London, United Kingdom
| | | | - Rana M. Safdar
- National Emergency Operation Centre, Ministry of National Health Services, Regulations and Coordination, Islamabad, Pakistan
| | - Andrew Etsano
- National Primary Health Care Development Agency, Abuja, Nigeria
| | | | | | - Nicholas C. Grassly
- Department of Infectious Disease Epidemiology, St Mary’s Campus, Imperial College London, London, United Kingdom
| | - Isobel M. Blake
- Department of Infectious Disease Epidemiology, St Mary’s Campus, Imperial College London, London, United Kingdom
- * E-mail:
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Kraan H, van der Stel W, Kersten G, Amorij JP. Alternative administration routes and delivery technologies for polio vaccines. Expert Rev Vaccines 2016; 15:1029-40. [DOI: 10.1586/14760584.2016.1158650] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Heleen Kraan
- Department of Research, Intravacc (Institute for Translational Vaccinology), Bilthoven, The Netherlands
| | - Wanda van der Stel
- Division of Drug Delivery Technology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Gideon Kersten
- Department of Research, Intravacc (Institute for Translational Vaccinology), Bilthoven, The Netherlands
- Division of Drug Delivery Technology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Jean-Pierre Amorij
- Department of Research, Intravacc (Institute for Translational Vaccinology), Bilthoven, The Netherlands
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Zumla A, Maeurer M. Host-Directed Therapies for Tackling Multi-Drug Resistant Tuberculosis: Learning From the Pasteur-Bechamp Debates. Clin Infect Dis 2015. [PMID: 26219693 DOI: 10.1093/cid/civ631] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Tuberculosis remains a global emergency causing an estimated 1.5 million deaths annually. For several decades the major focus of tuberculosis treatment has been on antibiotic development targeting Mycobacterium tuberculosis. The lengthy tuberculosis treatment duration and poor treatment outcomes associated with multi-drug resistant tuberculosis (MDR-TB) are of major concern. The sparse new tuberculosis drug pipeline and widespread emergence of MDR-TB signal an urgent need for more innovative interventions to improve treatment outcomes. Building on the historical Pasteur-Bechamp debates on the role of the "microbe" vs the "host internal milieu" in disease causation, we make the case for parallel investments into host-directed therapies (HDTs). A range of potential HDTs are now available which require evaluation in randomized controlled clinical trials as adjunct therapies for shortening the duration of tuberculosis therapy and improving treatment outcomes for drug-susceptible tuberculosis and MDR-TB. Funder initiatives that may enable further research into HDTs are described.
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Affiliation(s)
- Alimuddin Zumla
- Center for Clinical Microbiology, Division of Infection and Immunity, University College London (UCL) and NIHR Biomedical Research Centre, UCLHospitals NHS Foundation Trust, United Kingdom
| | - Markus Maeurer
- Therapeutic Immunology, Departments of Laboratory Medicine and Microbiology, Tumour and Cell Biology, Karolinska Institute, Stockholm, Sweden
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Wassilak SGF, Oberste MS, Tangermann RH, Diop OM, Jafari HS, Armstrong GL. Progress toward global interruption of wild poliovirus transmission, 2010-2013, and tackling the challenges to complete eradication. J Infect Dis 2014; 210 Suppl 1:S5-15. [PMID: 25316873 PMCID: PMC4615678 DOI: 10.1093/infdis/jiu456] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Despite substantial progress, global polio eradication has remained elusive. Indigenous wild poliovirus (WPV) transmission in 4 endemic countries (Afghanistan, India, Nigeria, and Pakistan) persisted into 2010 and outbreaks from imported WPV continued. By 2013, most outbreaks in the interim were promptly controlled. The number of polio-affected districts globally has declined by 74% (from 481 in 2009 to 126 in 2013), including a 79% decrease in the number of affected districts in endemic countries (from 304 to 63). India is now polio-free. The challenges to success in the remaining polio-endemic countries include (1) threats to the security of vaccinators in each country and a ban on polio vaccination in areas of Afghanistan and Pakistan; (2) a risk of decreased government commitment; and (3) remaining surveillance gaps. Coordinated efforts under the International Health Regulations and efforts to mitigate the challenges provide a clear opportunity to soon secure global eradication.
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Thompson KM, Pallansch MA, Duintjer Tebbens RJ, Wassilak SG, Kim JH, Cochi SL. Preeradication vaccine policy options for poliovirus infection and disease control. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2013; 33:516-43. [PMID: 23461599 PMCID: PMC7941951 DOI: 10.1111/risa.12019] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
With the circulation of wild poliovirus (WPV) types 1 and 3 continuing more than a decade after the original goal of eradicating all three types of WPVs by 2000, policymakers consider many immunization options as they strive to stop transmission in the remaining endemic and outbreak areas and prevent reintroductions of live polioviruses into nonendemic areas. While polio vaccination choices may appear simple, our analysis of current options shows remarkable complexity. We offer important context for current and future polio vaccine decisions and policy analyses by developing decision trees that clearly identify potential options currently used by countries as they evaluate national polio vaccine choices. Based on a comprehensive review of the literature we (1) identify the current vaccination options that national health leaders consider for polio vaccination, (2) characterize current practices and factors that appear to influence national and international choices, and (3) assess the evidence of vaccine effectiveness considering sources of variability between countries and uncertainties associated with limitations of the data. With low numbers of cases occurring globally, the management of polio risks might seem like a relatively low priority, but stopping live poliovirus circulation requires making proactive and intentional choices to manage population immunity in the remaining endemic areas and to prevent reestablishment in nonendemic areas. Our analysis shows remarkable variability in the current national polio vaccine product choices and schedules, with combination vaccine options containing inactivated poliovirus vaccine and different formulations of oral poliovirus vaccine making choices increasingly difficult for national health leaders.
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Affiliation(s)
- Kimberly M Thompson
- Kid Risk, Inc., , 10524 Moss Park Rd., Ste. 204-364, Orlando, FL 32832, USA.
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Patriarca PA. Research and development and the polio eradication initiative: too much, too soon...too little, too late? Clin Infect Dis 2012; 55:1307-11. [PMID: 22911643 DOI: 10.1093/cid/cis720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Geldenhuys H, Waggie Z, Jacks M, Geldenhuys M, Traut L, Tameris M, Hatherill M, Hanekom WA, Sutter R, Hussey G, Mahomed H. Vaccine trials in the developing world: operational lessons learnt from a phase IV poliomyelitis vaccine trial in South Africa. Vaccine 2012; 30:5839-43. [PMID: 22835741 DOI: 10.1016/j.vaccine.2012.07.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 11/15/2011] [Accepted: 07/12/2012] [Indexed: 11/25/2022]
Abstract
BACKGROUND Conducting vaccine trials in developing nations is necessary but operationally complex. We describe operational lessons learnt from a phase IV poliomyelitis vaccine trial in a semi-rural region of South Africa. METHODS We reviewed operational data collected over the duration of the trial with respect to staff recruitment and training, participant recruitment and retention, and cold chain maintenance. RESULTS-LESSONS LEARNT: The recruitment model we used that relied on the 24h physical presence of a team member in the birthing unit was expensive and challenging to manage. Forecasting of enrolment rates was complicated by incomplete baseline data and by the linear nature of forecasts that do not take into account changing variables. We found that analyzing key operational data to monitor progress of the trial enabled us to identify problem areas timeously, and to facilitate a collegial problem-solving process by the extended trial team. Pro-actively nurturing a working relationship with the public sector health care system and the community was critical to our success. Despite the wide geographical area and lack of fixed addresses, we maintained an excellent retention rate through community assistance and the use of descriptive residential information. Training needs of team members were ongoing and dynamic and we discovered that these needs that were best met by an in-house, targeted and systemized training programme. The use of vaccine refrigerators instead of standard frost-free refrigerators is cost-effective and necessary to maintain the cold-chain. CONCLUSION Operational challenges of a vaccine trial in developing world populations include inexperienced staff, the close liaison required between researchers and public health care services, impoverished participants that require complex recruitment and retention strategies, and challenges of distance and access. These challenges can be overcome by innovative strategies that allow for the unique characteristics of the setting, trial population, and trial team.
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Affiliation(s)
- H Geldenhuys
- South African Tuberculosis Vaccine Initiative, Institute of Infectious Diseases and Molecular Medicine (IIDMM), University of Cape Town, South Africa.
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Mateen FJ, Shinohara RT, Sutter RW. Oral and inactivated poliovirus vaccines in the newborn: a review. Vaccine 2012; 31:2517-24. [PMID: 22728224 DOI: 10.1016/j.vaccine.2012.06.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 05/22/2012] [Accepted: 06/07/2012] [Indexed: 11/27/2022]
Abstract
BACKGROUND Oral poliovirus vaccine (OPV) remains the vaccine-of-choice for routine immunization and supplemental immunization activities (SIAs) to eradicate poliomyelitis globally. Recent data from India suggested lower than expected immunogenicity of an OPV birth dose, prompting a review of the immunogenicity of OPV or inactivated poliovirus vaccine (IPV) when administered at birth. METHODS We evaluated the seroconversion and reported adverse events among infants given a single birth dose (given ≤7 days of life) of OPV or IPV through a systematic review of published articles and conference abstracts from 1959 to 2011 in any language found on PubMed, Google Scholar, or reference lists of selected articles. RESULTS 25 articles from 13 countries published between 1959 and 2011 documented seroconversion rates in newborns following an OPV dose given within the first seven days of life. There were 10 studies that measured seroconversion rates between 4 and 8 weeks of a single birth dose of TOPV, using an umbilical cord blood draw at the time of birth to establish baseline antibody levels. The percentage of newborns who seroconverted at 8 weeks range from 6-42% for poliovirus type 1, 2-63% for type 2, and 1-35% for type 3. For mOPV type 1, seroconversion ranged from 10 to 76%; mOPV type 3, the range was 12-58%; and for the one study reporting bOPV, it was 20% for type 1 and 7% for type 3. There were four studies of IPV in newborns with a seroconversion rate of 8-100% for serotype 1, 15-100% for serotype 2, and 15-94% for serotype 3, measured at 4-6 weeks of life. No serious adverse events related to newborn OPV or IPV dosing were reported, including no cases of acute flaccid paralysis. CONCLUSIONS There is great variability of the immunogenicity of a birth dose of OPV for reasons largely unknown. Our review confirms the utility of a birth dose of OPV, particularly in countries where early induction of polio immunity is imperative. IPV has higher seroconversion rates in newborns and may be a superior choice in countries which can afford IPV, but there have been few studies of an IPV dose for newborns.
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Affiliation(s)
- Farrah J Mateen
- Polio Eradication Initiative, World Health Organization, Geneva, Switzerland
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Holmgren J, Svennerholm AM. Vaccines against mucosal infections. Curr Opin Immunol 2012; 24:343-53. [PMID: 22580196 DOI: 10.1016/j.coi.2012.03.014] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 03/27/2012] [Indexed: 01/05/2023]
Abstract
There remains a great need to develop vaccines against many of the pathogens that infect mucosal tissues or have a mucosal port of entry. Parenteral vaccination may protect in some instances, but usually a mucosal vaccination route is necessary. Mucosal vaccines also have logistic advantages over injectable vaccines by being easier to administer, having less risk of transmitting infections and potentially being easier to manufacture. Still, however, only relatively few vaccines for human use are available: oral vaccines against cholera, typhoid, polio, and rotavirus, and a nasal vaccine against influenza. For polio, typhoid and influenza, in which the pathogens reach the blood stream, there is also an injectable vaccine alternative. A problem with available oral live vaccines is their reduced immunogenicity when used in developing countries; for instance, the efficacy of rotavirus vaccines correlates closely with the national per capita income. Research is needed to define the impact of factors such as malnutrition, aberrant intestinal microflora, concomitant infections, and preexisting immunity as well as of host genetic factors on the immunogenicity of these vaccines.
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Affiliation(s)
- Jan Holmgren
- University of Gothenburg Vaccine Research Institute (GUVAX) & Department of Microbiology and Immunology, The Sahlgrenska Academy at University of Gothenburg, Sweden.
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