Abstract
We performed a retrospective descriptive analysis of adverse events following immunization (AEFI) surveillance data to systematically analyze the epidemiological characteristics and temporal trends of AEFI with the DTaP-IPV/Hib pentavalent vaccine in Huzhou city from 2012 to 2024. The overall AEFI reporting rate was 19.67/10,000, showing a significant upward trend (p < .001), peaking in 2018 (47.01/10,000). Non-serious AEFIs predominated (99.4%, 19.56/10,000), while serious AEFIs were rare (0.6%, 0.11/10,000). The most common adverse reactions included redness and swelling (13.48/10,000), induration (8.06/10,000), and fever (7.64/10,000). Allergic rash occurred at a rate of 0.53/10,000. Three serious AEFIs were reported, comprising one case of vaccine-associated henoch-schönlein purpura (HSP) and two coincidental events (thrombocytopenic purpura (TP) and pyemia). Redness and swelling increased from 54.1% after the 1st dose to 75.5% after the 4th (p = .001), while induration peaked at 45.1% following the 3rd dose. Following the Vaccine Administration Law, reporting rates increased significantly (p < .05) for total AEFI, general reaction, non-serious AEFI, redness and swelling and induration, but remained lower for abnormal and other allergic reactions (p < .05). The present results indicate that the majority of reactions are mild and self-limiting, with serious events remaining rare. This provides preliminary safety evidence for the use of the DTaP-IPV/Hib vaccine. While future research is needed to validate and further explore adverse reactions associated with DTaP-IPV/Hib vaccine.