Abstract:

Objective To analyze the distribution of suspected adverse events following immunization (AEFI) in Tongling City, evaluate the progress of AEFI surveillance, and provide evidence for safe implementation of immunization. Methods Case data of AEFI reported in Tongling City from 2017 to 2021 were collected through the National Immunization Planning Information Management System under the China Disease Prevention and Control Information System. The descriptive epidemiological method was used to analyze the incidence of AEFI, the time and population characteristics of AEFI cases, and the occurrence of AEFI in different vaccines. Results A total of 1 711 172 doses of vaccine were administered in the population living in Tongling City from 2017 to 2021, with 937 cases of AEFI reported. The average annual reported incidence was 54.76 per 100 000 doses. Of the AEFIs, 810 cases (86.45%) were associated with general reactions, 125 (13.34%) with abnormal reactions, and 2 (0.21%) with coincidental events. AEFI cases were primarily reported in between March and August (n=708, 75.56%). The number of male and female cases reported was 492 and 445, respectively, with a gender ratio of 1.11:1. AEFI cases were most seen in infants aged under 2 years (n=696, 74.28%). The vaccines with the highest reporting rates were live attenuated influenza vaccine (nasal spray) (250.94/100 000 doses), DTap-Hib tetanus vaccine (219.22/100 000 doses), and 13-valent pneumococcal conjugate vaccine (170.16/100 000 doses). 75.35% of AEFIs occurred within 24 hours after vaccination, and all cases improved or recovered. Conclusion The safety of vaccines in Tongling City was generally good, yet infants under 2 years old were the key population of AEFI cases.

Key words: Adverse events following immunization, Immunization, Monitoring, Tongling City