Immunogenicity of a three dose and five dose oral human rotavirus vaccine (RIX4414) schedule in south Indian infants

Abstract

AimThis study was undertaken to compare the immunogenicity of a three dose and five dose schedule of an oral live-attenuated human rotavirus vaccine, Rotarix® in south Indian infants. MethodHealthy infants (N=90), six to seven weeks of age were enrolled to receive three doses (n=45) or five doses of Rotarix vaccine (n=45) along with other scheduled vaccines, each dose separated by a four week interval. Blood samples were taken before vaccination and one month post-dose three in the Rotarix three dose group and one month post-dose five in the Rotarix five dose group; all were tested for anti-rotavirus IgA by an antibody sandwich enzyme immunoassay. ResultsAt baseline, >50% of infants had >20units of anti-rotavirus IgA. The seroconversion rates after three and five doses were low and not significantly different in the two groups. However, among vaccine responders, children seropositive at baseline showed a much greater absolute increase in IgA antibody levels than children seronegative at baseline. ConclusionsRotarix vaccine showed low immunogenicity in south Indian children and increasing the number of doses did not increase the proportion of infants seroconverting after vaccination.