Immunogenicity of the pentavalent rotavirus vaccine among infants in two developing countries in Asia, Bangladesh and Vietnam

Vaccine (Impact Factor: 3.62). 04/2012; Supplement(1):A106–A113.


Background: We evaluated the immunogenicity of the pentavalent rotavirus vaccine (PRV) in two GAVIeligible
Asian countries, Bangladesh and Vietnam, nested in a larger randomized, double-blind, placebocontrolled
efficacy trial conducted over a two-year period from 2007 through 2009.
Methods: 2036 infants were randomly assigned, in a 1:1 ratio, to receive three oral doses of PRV or
placebo approximately at 6, 10, and 14 weeks of age. Concomitant use of EPI vaccines, including oral
poliovirus vaccine (OPV) and diphtheria-tetanus-whole cell pertussis (DTwP) vaccine, was encouraged
in accordance to the local EPI schedule. A total of 303 infants were evaluated for immunogenicity and
blood samples were collected before the first dose (pD1) and approximately 14 days following the third
dose (PD3). The seroresponse rates (≥3-fold rise from pD1 to PD3) and geometric mean titers (GMTs)
were measured for anti-rotavirus immunoglobulin A (IgA) and serum neutralizing antibody (SNA) to
human rotavirus serotypes G1, G2, G3, G4, and P1A[8], respectively.
Results: Nearly 88% of the subjects showed a
≥3-fold increase in serum anti-rotavirus IgA response in
the analysis of the two countries combined. When analyzed separately, the IgA response was lower in
Bangladeshi children (78.1% [95% CI: 66.0, 87.5]) than in Vietnamese children (97.0% [95% CI: 89.6, 99.6]),
with a PD3 GMT of 29.1 (units/mL) and 158.5 (units/mL), respectively. In the combined population, the
SNA responses to the individual serotypes tested ranged from 10 (G3) to 50 (G1) percentage points lower
than the responses shown in the developed countries. However, the SNA response to G3 in Vietnamese
subjects was 37.3% (95% CI: 25.8, 50.0), which was similar to the G3 response rate in developed countries.
Conclusions: Three oral doses of PRV were immunogenic in two GAVI-eligible Asian countries: Bangladesh
and Vietnam. The GMTs of both the serum anti-rotavirus IgA and SNA responses were generally higher
in Vietnamese than in Bangladeshi children. The SNA responses varied by individual serotypes and were
lower than the results from developed countries. The clinical significance of these observations is not
understood because an immune correlate of protection has not been established.

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    • "He charged researchers to address key unknown issues such as performance of these live oral vaccines in routine programmatic use in LMIC, factors likely to drive a positive impact, whether vaccines will demonstrate herd immunity, and whether immunisation of infants in their first year will result in sustained protection up to the second and third years of life [1] [2] [3] [4] [5]. He further charged that reporting on emerging strains demanded intensified surveillance, although it is reassuring that clinical trials and post-licensure data from other settings show good evidence of protection against a range of strains with both rotavirus vaccines. "
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    ABSTRACT: The 8th African Rotavirus Symposium was held in Livingstone, Zambia from the 12-13 June 2014. Over 130 delegates from 35 countries - 28 from African nations - participated in this symposium, which included scientists, clinicians, immunisation managers, public health officials, policymakers and vaccine manufacturers. The theme for the symposium was Rotavirus Landscape in Africa-Towards Prevention and Control. At the time of the symposium, a total of 21 African countries had introduced the rotavirus vaccine into their national immunisation schedules. This meeting was particularly timely and relevant to review early data on vaccine adoption and impact from these countries. The concluding panel discussion proposed several recommendations for areas of focus moving forward in rotavirus advocacy and research. Copyright © 2015. Published by Elsevier Ltd.. All rights reserved.
    Vaccine 05/2015; 33(29). DOI:10.1016/j.vaccine.2015.04.002 · 3.62 Impact Factor

  • Vaccine 04/2012; 30 Suppl 1:A1-2. DOI:10.1016/j.vaccine.2011.10.108 · 3.62 Impact Factor
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    ABSTRACT: Background: Identifying an immunological correlate of protection for rotavirus vaccines (Rotarix [RV1] and RotaTeq [RV5]) would substantially facilitate testing of interventions for improving efficacy in developing countries and evaluating additional candidate rotavirus vaccines. Methods: We accessed PubMed and to identify immunogenicity and efficacy trials for RV1 and RV5 to correlate anti-rotavirus serum immunoglobulin A (IgA) antibody titers vs efficacy in regions stratified by all-cause under-5 mortality rates (u5MR). We established a cutoff point for IgA geometric mean concentration or titer (GMC) that predicted lower efficacy and calculated pooled vaccine efficacy among countries with high vs low IgA titers. Findings: We observed an inverse correlation between u5MR and IgA titers for RV1 (r(2) = 0.72; P < .001 and RV5 (r(2) = 0.66; P < .001) and between efficacy and IgA titers for both vaccines (r(2) = 0.56; P = .005). Postimmunization anti-rotavirus IgA GMC <90 were associated with decline in vaccine efficacy. Efficacy during first 2 years of life was significantly lower among countries with IgA GMC < 90 (44%; 95% confidence interval [CI], 30-55) compared to countries with GMC > 90 (85%; 95% CI, 82-88). Interpretation: We observed a significant correlation between IgA titers and rotavirus vaccine efficacy and hypothesize that a critical level of IgA antibody titer is associated with a sufficient level of sustained protection after rotavirus vaccination.
    The Journal of Infectious Diseases 04/2013; 208(2). DOI:10.1093/infdis/jit166 · 6.00 Impact Factor
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