Epidemic characteristics and influencing factors of influenza outbreaks in Hunan Province, 2019-2021
CHEN Li-li1, ZENG Ge2, LIU Zi-yan2, LUO Kai-wei2, HU Shi-xiong2, ZHAN Zhi-fei2, HUANG Chao-yang2, LIU Ai-zhong1, CHEN Meng-shi1
1. Xiangya School of Public Health, Central South University, Changsha, Hunan 410078, China; 2. Hunan Provincial Center for Disease Control and Prevention, Changsha, Hunan 410005, China
Abstract：Objective To analyze the epidemic characteristics of outbreaks of influenza like illness (ILI) cases and their influencing factors in Hunan Province from 2019 to 2021, and to provide evidence for effective prevention of influenza outbreaks and scientific formulation of influenza prevention and control strategies. Methods The relevant data regarding ILI outbreaks in Hunan Province from 2019 to 2021 were collected to grasp the epidemic characteristics of the outbreaks and analyze the factors affecting the incidence rate and duration of influenza outbreaks. Results A total of 345 influenza outbreaks were reported in Hunan Province from 2019 to 2021, with an average incidence rate of 3.77%. The peak of outbreak reports was in March-May as well as November-January, with 283 (82.03%) cases reported. Primary and secondary schools were the main places where outbreaks occurred, with 333 (96.52%) cases reported. The top three regions with the highest number of reported outbreaks were Changsha City (25.22%, 87/345), Loudi City (15.07%, 52/345), and Xiangxi Tujia and Miao Autonomous Prefecture (14.49%, 50/345). Laboratory test results revealed that influenza A (H3N2) and B (Victoria) viruses were predominant, with 154 (44.64%) cases of A (H3N2) and 136 (39.42%) cases of B (Victoria). School type, availability of school doctor/clinic, reporting area and school size were related to the incidence rate of influenza outbreaks (P<0.05). School type, mode of suspension from school, time of taking measures, reporting area and school size were associated with the duration of influenza outbreaks (P<0.05). Conclusion Influenza outbreaks had obvious seasonality. Primary and secondary schools were places with highincidence of influenza outbreaks. It is necessary to strengthen the surveillance on outbreaks of ILI cases in schools, guide schools to implement comprehensive prevention and control measures, and effectively prevent influenza outbreaks in groups.
2023, Vol. 30 
