[Post-marketing safety analysis of inactivated enterovirus A71 vaccines]

Objectives: To evaluate the safety of inactivated enterovirus A71(EV-A71) vaccines after large-scale immunization in the community. Methods: We selected EV-A71 susceptible people (healthy children) aged 6-59 months in vaccination clinics from 89 counties in Zhejiang Province between April 2016 and March 2018. All local and systematic adverse actions were collected by 30 min on-site inspection, within 3 days and 4-30 days follow-up. Chi-square test and Fisher's exact test were used to compare the difference of AEs incidence in various characteristics among two groups. Results: A total of 71 663 doses of vaccines were included for active safety analysis, which included 37 331 doses in boys and 34 332 doses in girls. Among all the doses, children aged 6 to 11 months, 12 to 23 months and 24 to 59 months were received 13 707, 32 639 and 25 317 doses respectively. The incidence of adverse reactions within 30 min, 3 days and 4-30 days were 0.33% (239 doses), 1.58% (1 133 doses) and 0.34% (244 doses) respectively. Adverse reactions within 3 days were 1 372 doses, with a incidence of 1.91%; among all the cases, 539 doses (0.75%) were grade 1, 677 doses (0.94%) were grade 2 and 156 doses (0.22%) were grade 3, no grade-4 adverse reaction was reported. The common local adverse reactions were redness, swelling and pruritus, with the incidence rates were 0.05% (39 doses), 0.02% (16 doses) and 0.02% (12 doses), respectively, while the most common systemic adverse reaction was pyrexia with an incidence of 1.19% (856 doses), followed by diarrhea and anorexia with the incidence rates were 0.15% (104 doses) and 0.13% (90 doses) respectively. Conclusion: Most adverse actions of EV-A71 vaccines were mild and moderate and majority of them were common adverse actions. No new adverse reactions were found in the study.