[Analysis of serious adverse events following immunization in Zhejiang Province from 2015 to 2024]

Objective: To analyze the serious AEFI reported in Zhejiang Province from 2015 to 2024, and evaluate the vaccine safety. Methods: Serious AEFI cases reported in Zhejiang Province from 2015 to 2024 were collected through China's AEFI Information Management System, including demographic information, vaccination information, clinical incidence and treatment history, investigation and diagnosis information, etc. Descriptive methods were used to analyze and evaluate the regional distribution, seasons, populations, vaccines, and clinical diagnosis and classification. Results: The incidence rates of serious AEFI and abnormal reactions showed statistically significant differences with annual changes. There were significant differences in reported cases among different regions, with a male-to-female ratio of 1.25∶1.95, 11% of cases were under 1 year old, and 67.26% had received one suspected vaccine. The incidence rates of serious adverse reactions to the HZV, BCG, DTaP, IPV/Hib, RabV, and PPV23 were notably high, ranking among the top five for all vaccines, with rates of 16.18 per million, 6.61 per million, 5.90 per million, 5.21 per million, and 4.30 per million, respectively. In serious abnormal reactions, the incidence of clinical diagnostic reports such as thrombocytopenic purpura, febrile seizures, allergic purpura, anaphylactic shock, and BCG lymphadenitis was relatively high. Conclusion: From 2015 to 2024, the post-vaccination safety profile in Zhejiang Province remained favorable, with no significant increase in the incidence of severe adverse reactions compared to the 2013-2014 period. Notably, heightened vigilance is warranted for acute allergic reactions, and sustaining elevated monitoring sensitivity and reporting quality remains imperative.