LAUSR

AIMS The bivalent oral poliovirus vaccine (bOPV; types 1 and 3) replaced the trivalent OPV (tOPV; types 1, 2 and 3) globally in April, 2016. A routine schedule of 1 dose of inactivated poliovirus vaccine (IPV) and a subsequent 3 doses of bOPV was implemented in Jiangsu simultaneously. The schedule was changed to "2 IPV+2 bOPV" on September 1, 2019. Although OPV type 2 has been removed, challenges persist because of adverse events following immunization (AEFIs) with bOPV. Therefore, we analysed and evaluated the safety profile of bOPV administered in children based on passive postmarketing AEFI surveillance. METHODS We collected all bOPV-related AEFI reports in Jiangsu from the Chinese National AEFI Information System (CNAEFIS) between May 2016 and April 2020. We obtained the administered doses of bOPV from the Jiangsu Provincial Electronic Immunization Registries System. A descriptive analysis was performed. RESULTS In total, 2,084 bOPV-related AEFIs were retrieved from the CNAEFIS. The overall reporting rate was 24.16 per 100,000 doses. Most AEFIs were nonserious. The most frequently reported symptoms were fever, rash and gastrointestinal disorders. Only 1.34% of AEFIs were serious, in which thrombocytopenic purpura accounted for the largest category. Seventeen serious adverse events, including two vaccine-associated paralytic poliomyelitis (VAPP) cases, were considered to be related to bOPV vaccination. The rate of VAPP was 0.2 per million doses. CONCLUSION AEFI analysis showed that bOPV was well tolerated. The events most frequently reported were nonserious. However, bOPV can still cause VAPP. Attention should be given to risks related to bOPV.