Epidemiological Characteristics on Outbreaks of Influenza in Wanzhou of Chongqing from 2018 to 2022

Wang Hengqin; Zheng Jinfeng; Gan Yulu; Wang Yi; Lang Zhongkai

doi:10.3969/j.issn.1001-568X.2024.11.0017

Abstract：OBJECTIVE To analyze the epidemiological characteristics of infectious diseases influenza outbreaks in Wanzhou of Chongqing,and provide a scientific basis for prevention and control strategies.METHODS The data on influenza outbreaks in schools in Wanzhou of Chongqing from 2018 to 2022 from the National Emergency Public Health Events Information Management System and on-site epidemiological surveys were collected and analyzed using descriptive epidemiology method.RESULTS From 2018 to 2022,55 outbreaks of influenza cases were reported and 51 were confirmed in the laboratory,with a cumulative incidence of 4 760 cases and an incidence rate of 4.19%(4 760/113 665).Among them,there were 20 outbreaks of type A pdm09(H1N1),15 outbreaks of type B(Victoria),10 outbreaks of type A(H3N2)and 6 outbreaks of mixed infection of type A(H1N1)pdm09/A(H3N2).The epidemic mainly occurred in March and December,accounting for 54.90%(28/51)and 23.53%(10/51)respectively.The incidence of the epidemic is mainly concentrated in primary and secondary schools,accounting for 72.55%(37/51)and 17.65%(9/51)respectively.Logistic regression analysis showed that virus type and intervention time were significant factors affecting the duration of influenza outbreaks,and the OR accounted for 87.897(95%CI:7.478～1 033.815)and 0.085(95%CI:0.014～0.505)of the total number of outbreaks,respectively.CONCLUSION The influenza outbreak in Wanzhou District mainly occurs in winter and spring,and the high-risk population is the primary and secondary school population.Type A and type B influenza virus showed alternating change with seasons.Among them,the outbreak caused by H1N1 virus has a relatively large scale and relatively long duration,and early intervention has a great impact on epidemic control.