Adverse events following immunization of bivalent types 1 and 3 oral poliovirus attenuated live vaccines in Zhejiang province: analysis on surveillance data of 2016 – 2018

  Objective  To analyze the incidence of reported adverse events following immunization（AEFI）of bivalent type 1 and type 3 oral poliovirus attenuated live vaccine (bOPV) in Zhejiang province and to evaluate the safety of bOPV vaccination.

  Methods  The AEFI surveillance data of bOPV in Zhejiang province from May 2016 to October 2018 were collected through the national AEFI surveillance information system for the descriptive analysis.

  Results  From May 2016 to October 2018, totally 378 bOPV-related AEFI were reported in Zhejiang province and the reported incidence rate was 7.96/100 000 doses. Of all the AEFI reported, 278 (73.54%) were common reactions, with a reported incidence rate of 5.86/100 000 doses; 81 (21.43%) were abnormal reactions, with a reported incidence rate of 1.71/100 000 doses; 17 (4.50%) were coincidental and 2 (0.53%) were undetermined. For all the AEFI reported, 260 (68.78%) and 104 (27.51%) occurred among the children aged less than one year and those aged 4 years, which were in accordance with the ages the vaccinees and vaccination doses required by immunization schedule. There were 92.33% of the reported AEFI occurred within one day after the inoculation. Two cases of severe abnormal thrombocytopenic purpura, one case of vascular edema and two cases of coincidental death (accidental asphyxia and toxic shock caused by acute intestinal necrosis, respectively) were reported.

  Conclusion  The results indicated that the vaccination of bOPV is generally safe in Zhejiang province. However, attention should be paid to the occurrence of rare severe reactions of bOPV vaccination.