Poliomyelitis vaccination of infants: preimmunization status and seroconversion.

A study was carried out in Delhi on the preimmunization status of infants aged 2-6 months with regard to poliomyelitis and on seroconversion after the administration of oral poliomyelitis vaccine. It was found that 30.3% of the 204 infants included in the study excreted enteroviruses, 58% of which were found to be polioviruses. Of 197 sera examined for neutralizing antibodies against different types of poliovirus, 73% were found to be triple negative and only 4.0% triple positive. Three doses of oral poliomyelitis vaccine were administered at intervals of 1 month. It was found that 71.8% of the vaccinated infants excreted cytopathogenic agents in the 7 days following the first dose; 80.4% of these agents were found to be polioviruses. Seroconversion was studied in 71 infants, and good antibody responses to all three types of poliovirus were observed.