ABSTRACT
Objective@#To analyze the epidemiological characteristics of influenza clusters in Hangzhou from 2018 to 2019, so as to provide references for the prevention and control of influenza. @*Methods@#The data came from the epidemic investigation reports of influenza clusters in Hangzhou from the 27th week of 2018 and the 26th week of 2019. The time distribution, school types, population distribution and etiology of influenza were analyzed. Multivariate logistic regression model was employed to analyze the influencing factors for the attack rate of influenza clusters. @*Results@#During the surveillance season, a total of 231 school influenza clusters involving 4 233 cases were reported. The median of the attack rate was 21.74%. The peak of the clusters was in March 2019, with 89 events and 1 476 cases ( 34.87% ). The clusters occurred mainly in primary schools ( 188 events, 81.39% ) and were mainly caused by Victoria-like strains of influenza B virus ( 84 events, 36.36% ). The multivariate logistic regression analysis indicated that infection of teachers increased the risk of high attack rate ( OR=3.133, 95%CI: 1.180-8.320 ), and kindergartens had higher risk of high attack rate than primary schools ( OR=4.123, 95%CI: 1.579-10.763 ). @*Conclusions@#The influenza clusters in Hangzhou from 2018 to 2019 is mainly caused by Victoria-like strains of influenza B virus. Kindergartens and teachers are the key points for the prevention and control of influenza clusters.