Adverse events following immunization of bivalent oral poliovirus vaccines in Hebei province: analysis on surveillance data

  Objective  To evaluate the safety of bivalent oral poliovirus vaccine (bOPV) inoculation in Hebei province.

  Methods  We extracted data on adverse events following immunization (AEFI) in Hebei province during 2015 and between May and December 2016 through National Surveillance System for AEFI; then we analyzed the data using descriptive epidemiology methods.

  Results  The reported incidence of AEFI related to bOPV was 155.97 per million inoculations between May and December 2016 and the AEFI incidence related to trivalent oral poliovirus vaccine (tOPV) was 88.29 per million inoculations in 2015 in Hebei province. The reported cases of AEFI were mostly common reactions among small children ≤ one year old and among those receiving their first vaccine inoculation. The estimated AEFI incidence related to bOPV inoculation was significantly higher than that related to tOPV inoculation. A higher proportion of AEFI was observed among the reported cases receiving a single bOPV inoculation. No significant differences were observed in AEFI incidence between bOPV and tOPV among the inoculated children at various month age and with different dose order and in the time interval from the inoculation to the incident of adverse reaction.

  Conclusion  The estimated incidence of bOPV-related AEFI in Hebei province is higher than that in China. Continuous surveillance on bOPV-related AEFI needs to be strengthened.