This study aimed to evaluate the effect of maternally derived antibody on the immunogenicity of Sabin IPV. A total of 600 infants were randomized to receive one of the five different vaccines: the high- (group A), medium- (group B) or low-dose (group C) of investigational Sabin IPV, the control Salk IPV (group D) or the control Sabin IPV (group E), at 2, 3 and 4 months of age. The post-vaccination GMTs, GMIs and seroconversion rates of poliovirus type-specific neutralizing antibody were analyzed for different maternal antibody levels. The correlations between maternal antibody levels and post-vaccination antibody responses were also modeled by linear regressions. The post-vaccination GMTs were significantly lower among infants with high maternal antibody titers for poliovirus type 1 or 2 mainly in the groups B, C, D and E. The GMIs and seroconversion rates decreased significantly with the increase of maternal antibody levels in all the five groups. In the groups A, B and C, maternal antibody levels were negatively associated with the post-vaccination antibody titers (for poliovirus type 1 and 2) and the fold increases of post-vaccination antibody (for all the 3 poliovirus types). With the reduce of potency of the investigational Sabin IPVs, the linear regression coefficients increased accordingly in the groups A, B and C. In conclusion, high levels of maternal poliovirus antibody could attenuate the immune responses to the Sabin IPVs. Altering the potency of the investigational Sabin IPVs could alter the associations between maternal antibody levels and the serologic responses of infants.
Keywords: Maternal antibody; Sabin strains; immune response; inactivated poliovirus vaccine.