Surveillance of adverse events following immunization in Jinhua, Zhejiang, 2006-2012

Objective To understand the incidence pattern of adverse events following immunization (AEFI) in Jinhua, Zhejiang province, and evaluate the performance of AEFI surveillance system. Methods The incidence data of AEFI in Jinhua from 2006 to 2012 was collected through national immunization program surveillance system and AEFI information system to conduct descriptive methodological analysis. Results A total of 539 AEFI cases were reported during this period. The cases aged ≤1 year accounted for 30.98%. The AEFI cases were mainly caused by the vaccines used in national immunization program (NIP), accounting for 71.43%. Mild cases accounted for 48.42%, severe reactions accounted for 40.82%. Among these cases, 79.41% occurred within 1 day after vaccination. Fever/red swelling/scleroma was the main clinical manifestation, accounting for 35.99%; and the major severe reaction was anaphylactic rash, accounting for 54.09％. Totally 524 cases (97.21%) were cured, 1 case (0.19%) was fatal and 3 cases (0.56%) had sequela. AEFI cases were reported in all 9 counties in Jinhua every year. The reporting rate within 48 h was 85.71％, and the investigating rate within 48 h was 76.81％. The completeness rate of reporting card was 94.25%. Conclusion The results showed that the quality of AEFI surveillance increased year by year, but the sensitivity of the surveillance system was still low, especially for the mild reaction. AEFI often occurs in young children within 1 day after the immunization of NIP vaccines. It is important to improve the compensation mechanism of AEFI, strengthen supervision and conduct training and effective communication with press to improve the quality and sensitivity of AEFI surveillance.