Passive surveillance of adverse events following immunization for National Immunization Program vaccines in Shenyang, China, 2009-2024.

Based on the Chinese National Adverse Events Following Immunization Surveillance Information System (CNAEFIS), a descriptive epidemiological analysis was conducted on Adverse Events Following Immunization (AEFI) of National Immunization Program (NIP) vaccines in Shenyang from 2009 to 2024, to understand the distribution characteristics and reporting status of AEFI using passive surveillance data in the region. Reaction types were classified according to national unified surveillance standards. Descriptive epidemiological analysis was carried out from temporal, regional, demographic and vaccine-specific distributions, and AEFI reporting rate was calculated. From 2009 to 2024, a total of 3,420 cases of AEFI associated with NIP vaccines were reported, with an annual average reporting rate of 15.8 per 100,000 doses. Among these, the reporting rate of common vaccine reactions was 14.87 per 100,000, and that of rare vaccine reactions was 0.54 per 100,000. Differences in reporting rates between districts were statistically significant (χ2 = 618.9, p < .05). Most reported events were common reactions, and rare reactions were infrequently reported. There were obvious regional disparities in AEFI surveillance performance. Surveillance training and management should be further strengthened in low-reporting districts to reduce regional gaps and improve overall reporting performance.