[Study on surveillance data of adverse events following immunization of seasonal influenza vaccine in China during 2015-2018 influenza season].

Objective: To analyze the occurrence features of adverse events following immunization (AEFI) of Seasonal Influenza Vaccines (InfV) used in China, 2015-2018 influenza season. Methods: InfV (including concurrent administered with other vaccines) AEFI data were collected through the Chinese national AEFI information system during 2015.9.1-2018.8.31 (excluding Chinese Hong Kong, Macao and Taiwan data). The vaccine lot release data were collected from National Institutes for Food and Drug Control published database. Time periods of three influenza season were 2015.9.1-2016.8.31, 2016.9.1-2017.8.31, 2017.9.1-2018.8.31. The vaccines used and included in this analysis were trivalent inactivated influenza vaccine (IIV3)-Split, IIV3-Split (Children) and IIV-subnit. The incidence of AEFI were calculated (per 100 000 release doses), and epidemiological characteristic were analyzed using descriptive methodology. Results: A total of 8 464 InfV AEFIs were collected in 2015-2018 influenza season from National AEFI Information System, in which 5 646 were IIV3-split, with the rate of 10.64/100 000 release doses, 2 818 were IIV3-split (Children), with the rate of 9.355/100 000 release doses. The most common symptom was fever (axillary temperature ≥37.1 ℃) within vaccine reactions, with a number of 6 207 cases. In which, there were 3 554 cases with fever (axillary temperature ≥38.6 ℃) and the estimated reporting rate was 4.274/100 000 release doses. In all rare vaccine reactions, the most common diagnosis was anaphylactic rash(442, 0.531/100 000 release doses) and angioedema (70, 0.084/100 000 release doses). Even the rates of serious rare vaccine reactions were low, febrile Convulsion (27, 0.032/100 000 release doses) and Henoch-Schönlein Purpura(HSP) (21, 0.025/100 000 release doses) were relatively common in serious rare vaccine reactions during the study period. Conclusion: The estimated rate of rare vaccine reactions related toInfV was relatively low. In all vaccine reactions, fever was the most common symptoms. The most common diagnosis of non-serious rare vaccine reaction were anaphylactic rash and angioedema. The incidence of serious rare vaccine reactions was low.