A real-world based study for immunogenicity and safety for three immunization schedules of polio vaccine.

To evaluate the immunogencity and safety for three immunization schedules of inactivated poliovirus vaccine (IPV) and bivalent oral poliovirus vaccine (bOPV) for providing a basis for further optimization of the polio sequential immunization schedule. To obtain immunogenicity data and to active surveillance the occurrence of adverse events following immunization (AEFI), healthy infants ≥ 2 months of age were randomly chosen in Hebei Province, and were divided into three groups to be vaccinated with IPV-bOPV-bOPV(Group a), IPV-IPV-bOPV(Group b) and IPV-IPV-IPV(Group c) at 2, 3 and 4 months of age respectively. AEFI cases related to poliomyelitis vaccines in Hebei province by passive surveillance from January 1, 2018 to December 31, 2022 were obtained from national adverse event following immunization surveillance system (NAEFISS). After basic immunization with polio vaccine, the positive conversion rate of neutralizing antibodies of types I, II and III were all > 97.00% and the positive rates were all > 98.00%, the geometric mean titer (GMT) was significantly higher than that before basic immunization, the GMT level of neutralizing poliovirus antibody after basic immunization was the highest in type I, followed by type III, and the lowest in type II. A total of 16 AEFI cases (2.52%) were reported by active surveillance, and 2903 AEFI cases (1.40%) were reported by passive surveillance. AEFI reported by both monitoring modalities were dominated by fever of common vaccine reactions. No rare serious adverse reactions like VAPP etc. were monitored and the overall regression was positive. All three immunization schedules for polio vaccine have demonstrated good immunogenicity and safety when administered to healthy populations.