Antibody response of children immunized with poliovaccines: an evaluation using two strains of poliovirus type 1.

Neutralizing antibody response of children immunized with either OPV (3 doses), or IPV (2 doses) was evaluated against poliovirus type 1 Sabin vaccine strain and a local neurovirulent isolate. Both vaccines elicited significantly better antibody response against the vaccine strain than against the neurovirulent isolate. Moreover, approximately 35 per cent of sera contained very low levels of antibody against the virulent virus in spite of good antibody titre against the vaccine strain. The observed difference in antibody response to the wild and the vaccine strains was significant. The differential immune response could be one of the reasons of paralytic disease observed even after administration of OPV (3), in some children if infecting virus dose is high, as in case of urban slums in endemic areas.