ABSTRACT
Objective@#To investigate the epidemiological characteristics of influenza outbreaks in Zhejiang Province from 2013 to 2022, so as to provide insights into influenza prevention and control. @*Methods@#Data pertaining to influenza outbreaks reported in Zhejiang Province from 2013 to 2022 were collected from National Influenza Surveillance System in China, including time, region, cases and pathogen types of influenza outbreaks. The temporal, spatial and pathogen distribution of influenza outbreaks were analyzed using a descriptive epidemiological method. @*Results@#A total of 577 influenza outbreaks involving 448 698 individuals were reported in Zhejiang Province from 2013 to 2022, and the overall attack rate was 5.34% (23 974 cases), with no death reported. The lowest attack rate of influenza was 0.26%, and the highest was 80.00%, with a median attack rate of 10.89% (interquartile range, 24.26%). The outbreak had the shortest duration of 1.00 day, and the longest duration of 59.00 days, with a median duration of 9.00 (interquartile range, 11.00) days. There were 387 influenza outbreaks that occurred between November and January of the following year (67.07%), and the three highest numbers of outbreaks were reported in Hangzhou City (310 outbreaks), Wenzhou City (51 outbreaks) and Jinhua City (46 outbreaks). There were 395 outbreaks reported in urban regions (68.46%), 93 in counties and townships (16.12%) and 89 in rural regions (15.42%), and influenza outbreaks predominantly occurred in primary schools (487 outbreaks, 84.40%). In addition, the types of pathogens were alternately prevalent, with influenza B virus (241 outbreaks, 41.77%) and A/H3N2 virus (232 outbreaks, 40.21%) as predominant subtypes. @* Conclusions@#Influenza outbreaks mainly occurred in winter in Zhejiang Province from 2013 to 2022, and primary schools were main places of influenza outbreaks, while influenza B virus and A/H3N2 virus were predominant subtypes. It is necessary to reinforce the surveillance and report of influenza-like illness in schools and improve the coverage of influenza vaccination to prevent influenza outbreaks.