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Published on: January 28, 2019
Immunogenicity of the pentavalent rotavirus vaccine in African infants
George E Armah1, Robert F Breiman, Milagritos D Tapia
1Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana.
Insights
The pentavalent rotavirus vaccine (PRV) showed immunogenicity in African infants, with similar antibody responses across Ghana, Kenya, and Mali. However, these responses were lower than in Europe and the USA, potentially impacting vaccine efficacy.
Area of Science:
- Vaccinology
- Pediatrics
- Infectious Diseases
Background:
- Rotavirus gastroenteritis (RVGE) is a major cause of infant mortality in Africa.
- The pentavalent rotavirus vaccine (PRV) has demonstrated efficacy in developed countries.
- Assessing PRV immunogenicity in African infants is crucial for understanding its potential impact in diverse populations.
Purpose of the Study:
- To evaluate the immunogenicity of the pentavalent rotavirus vaccine (PRV) in African infants.
- To compare PRV immune responses in Ghana, Kenya, and Mali.
- To investigate potential reasons for observed differences in immunogenicity compared to studies in developed countries.
Main Methods:
- A double-blind, placebo-controlled, multicenter Phase III clinical trial involving 5468 infants in Ghana, Kenya, and Mali.
- Administration of 3 doses of PRV or placebo at approximately 6, 10, and 14 weeks of age.
- Measurement of serum anti-rotavirus IgA and serum neutralization antibody (SNA) responses to specific rotavirus serotypes pre- and post-vaccination.
Main Results:
- PRV was immunogenic in African infants, with pooled anti-rotavirus IgA sero-response rates of 78.3%.
- IgA response rates were consistent across the three African sites (73.8%-82.5%) but lower than those reported in Europe and the USA.
- Serum neutralization antibody (SNA) geometric mean titers (GMTs) were 3-4 fold lower compared to studies in developed countries.
Conclusions:
- The pentavalent rotavirus vaccine (PRV) is immunogenic in African infants, demonstrating consistent antibody responses across different African sites.
- Observed lower immunogenicity (IgA and SNA responses) compared to developed countries may correlate with lower vaccine efficacy.
- Further research is needed to elucidate the factors contributing to the reduced immunogenicity in African infants.
Abstract:
We recently completed a double-blind, placebo-controlled, multicenter Phase III clinical trial of the pentavalent rotavirus vaccine (PRV) in three African countries, Ghana, Kenya, and Mali, from April 2007 to March 2009. The immunogenicity of PRV in African infants is described. In total, 5468 infants were randomized 1:1 to receive 3 doses of PRV or placebo at approximately 6, 10, and 14 weeks of age. Breastfeeding and concomitant administration of EPI vaccines, including OPV, were allowed, and HIV-infected infants were not excluded. Immunogenicity of PRV was assessed by measuring serum anti-rotavirus IgA responses, as well as serum neutralization antibody (SNA) to the human rotavirus serotypes G1, G2, G3, G4 and P1A[8] in approximately 150 infants per country. Sera were collected pre-dose 1 (pD1) and approximately 14 days post-dose 3 (PD3) for immunological analysis. For the sero-response rates (≥ 3-fold rise from pD1 to PD3), the number of subjects evaluable included those with both pD1 and PD3 data available. PRV was immunogenic in African children and significantly reduced severe RVGE in African children through the first two years of life. The pooled anti-rotavirus IgA sero-response rate was 78.3%, with consistent rates in each of the African sites: 73.8% (Kenya), 78.9% (Ghana), and 82.5% (Mali); but generally lower than that reported in Europe and USA. PD3 GMTs (28.2 dilution-units) were 5-10 times lower than those assessed in subjects in clinical trials in developed countries. SNA responses to human rotavirus serotypes G1-G4 and P1A[8] ranged from 6.3% (G3) to 26.5% (G4). PD3 SNA GMTs to G1 and P1A[8] were 4-fold and 3-fold lower respectively, when compared to the corresponding GMTs in subjects who received PRV in similar studies conducted in developed countries. PRV was immunogenic in African infants, and the anti-rotavirus IgA sero-response rates were similar across all three African sites although lower than those observed in Europe and USA. While immune correlates of protection have not been established for rotavirus, the findings are consistent with lower efficacy rates demonstrated during this trial. Further investigation is needed to understand the reason for the lower immunogenicity observed.
