Department of Pharmacy, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, China (People's Republic)
Background: Since 2016, vaccines against enterovirus 71 (EV71) infection have been approved for use in China. Reports to the national passive surveillance system raised concerns about Henoch‑Schönlein purpura (HSP) after EV71 vaccination. Rapid safety assessment of this novel vaccine is a public health priority.
Objectives: To assess risks of HSP following EV71 vaccination in China.
Methods: We used data from a Regional Health Information Platform in Ningbo from January 1, 2016 to December 31, 2019. The study population consisted of children 6 to 71 months of age who had at least 180 days of continuous enrolment in the database. The vaccine-exposed population was children who received any dose of EV71 vaccine. We implemented a multi-layered approach to active monitor HSP following EV71 vaccination that included near real-time surveillance using Poisson-based maximized sequential probability ratio test (PMaxSPRT) and further signal evaluation performing the self-controlled case series (SCCS) designs.
Results: A total of 999,894 children aged 6~71 months were included in the dynamic cohort from 2016 to 2019. A total of 326,820 EV71 doses were administered to the study population. During 157 weeks of sequential analyses, no statistically increased risks were detected, when compared with the background risk using PMaxSPRT. Further SCCS analyses confirmed no associations between EV71 vaccination and HSP (adjusted incidence rate ratio: 0.90, 95% CI: 0.44 to 1.85).
Conclusions: Our results reassured the safety of HSP after EV71 vaccination using post-licensure data for the first time.
