Poliomyelitis vaccination of infants: preimmunization status and seroconversion
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Pre-vaccination, many infants in Delhi lacked polio antibodies. Oral polio vaccination in infants showed good seroconversion, indicating vaccine effectiveness against poliomyelitis.
Area of Science:
- Pediatrics
- Virology
- Immunology
Background:
- Poliomyelitis remains a global health concern, necessitating effective vaccination strategies.
- Understanding pre-immunization antibody status is crucial for assessing vaccine efficacy.
- Infant populations in urban settings may have varying levels of endemic enterovirus exposure.
Purpose of the Study:
- To evaluate the pre-immunization serological status of infants in Delhi against poliovirus.
- To assess the seroconversion rates and virological response following oral poliomyelitis vaccine (OPV) administration.
- To identify enterovirus and poliovirus shedding in infants before and after OPV vaccination.
Main Methods:
- Cross-sectional study involving 204 infants aged 2-6 months in Delhi.
- Serological testing for poliovirus neutralizing antibodies in pre-vaccination sera.
- Administration of three doses of oral poliomyelitis vaccine at monthly intervals.
- Enterovirus and poliovirus detection in stool samples post-vaccination.
- Serological assessment of antibody response in a subset of 71 infants post-vaccination.
Main Results:
- Pre-vaccination, 73% of infants were triple-negative for poliovirus antibodies, and only 4% were triple-positive.
- Enteroviruses were excreted by 30.3% of infants, with 58% identified as polioviruses.
- Following the first OPV dose, 71.8% of infants shed cytopathogenic agents, 80.4% of which were polioviruses.
- Significant antibody responses to all three poliovirus types were observed in 71 vaccinated infants.
Conclusions:
- A substantial proportion of infants in Delhi exhibit low pre-existing immunity to poliomyelitis.
- Oral poliomyelitis vaccine elicits a robust seroconversion response in infants.
- The study highlights the importance of continued vaccination efforts to achieve polio eradication.
Abstract:
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.