Safety and immunogenicity of tetravalent rhesus-based rotavirus vaccine in Bangladesh

BACKGROUND.Rotavirus is the most common cause of severe gastroenteritis among children worldwide. OBJECTIVES.To compare the safety, immunogenicity and shedding patterns of rhesus rotavirus (RRV)-tetravalent vaccine vs. placebo among infants in rural Bangladesh. METHODS.A double blinded, placebo-controlled trial was conducted in which infants (n = 120) were randomly assigned to receive three doses of either vaccine or placebo administered at ∼6, 10 and 14 weeks of age together with routine immunizations. Data on possible adverse effects of vaccinations were collected daily for 7 days after each dose. Stool samples were collected after each dose, and serum samples were obtained before the first and after the third vaccination. RESULTS.Fever (≥38°C), as measured by study assistants, was noted more frequently among vaccinees (15%) than among placebo recipients (2%) during the 7 days after vaccination but was not reported more frequently by parents of vaccinees vs. placebo recipients. Overall 87% of vaccinees had an antibody response (measured by IgA or anti-RRV-neutralizing antibodies) after vaccination compared with 32% of placebo recipients. Rates of seroconversion were higher among subjects with lower levels of prevaccination antibodies and those who shed rotavirus after vaccination. Vaccine strain viruses were detected in stools from placebo vaccine recipients who had evidence of IgA seroconversion. CONCLUSIONS.In this population RRV-tetravalent vaccine was comparably immunogenic and safe as in trials conducted in developed countries, where this vaccine has been proved effective in preventing severe rotavirus diarrhea. These data support continued evaluation of rotavirus vaccines in developing countries.