L J Liu1, J Yang, F Zhu, L J Wang, Q Guo, J Tang, Q Q Fang, D Y Wang, T Chen. 1. Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Key Laboratory for Medical Virology, National Health, Beijing 102206, China.
Abstract
Objective: To analyze epidemiological characteristics of influenza-like illness outbreaks in mainland China during 2017-2018 surveillance season, and to provide scientific evidence for developing influenza prevention and control strategies. Methods: We collected the data on reported influenza outbreaks in 2017-2018 surveillance season from China Influenza Surveillance Information System and China Public Health Emergency Management Information System and analyzed the data of laboratory-confirmed influenza-like illness outbreaks by descriptive epidemiological methods. Results: During the surveillance season, a total of 2 398 influenza-like illness outbreaks (with 10 or more incidences in an outbreak) in mainland China were reported, involving 87 084 patients, of which 2 323 were influenza outbreaks, involving 85 531 patients. The reported influenza-like illness outbreaks occurred most frequently from November 2017 to January 2018 in both the southern and northern regions and the highest peaks were in December 2017. During the period 1 850 influenza-like illness outbreaks (77.15%) were reported in the southern region, and 548 influenza-like illness outbreaks (22.85%) were reported in the northern region. The most of the outbreaks occurred in primary, secondary schools and nursery care schools, with a total of 2 210 reports (92.16%). And the majority of the outbreaks involved 10-29 incident cases. The dominant isolated virus strains for the outbreaks were influenza B (1 505 outbreaks, 62.76% of all the outbreaks). Conclusion: Seasonality of influenza outbreaks were observed in mainland China during 2017-2018 surveillance season and the reported influenza outbreaks were most frequently occurred in autumn-winter season and in southern China. Primary, secondary schools and nursery care schools are high-risk places for outbreaks, and the dominant isolated virus strains for the outbreaks were influenza B.
Objective: To analyze epidemiological characteristics of influenza-like illness outbreaks in mainland China during 2017-2018 surveillance season, and to provide scientific evidence for developing influenza prevention and control strategies. Methods: We collected the data on reported influenza outbreaks in 2017-2018 surveillance season from China Influenza Surveillance Information System and China Public Health Emergency Management Information System and analyzed the data of laboratory-confirmed influenza-like illness outbreaks by descriptive epidemiological methods. Results: During the surveillance season, a total of 2 398 influenza-like illness outbreaks (with 10 or more incidences in an outbreak) in mainland China were reported, involving 87 084 patients, of which 2 323 were influenza outbreaks, involving 85 531 patients. The reported influenza-like illness outbreaks occurred most frequently from November 2017 to January 2018 in both the southern and northern regions and the highest peaks were in December 2017. During the period 1 850 influenza-like illness outbreaks (77.15%) were reported in the southern region, and 548 influenza-like illness outbreaks (22.85%) were reported in the northern region. The most of the outbreaks occurred in primary, secondary schools and nursery care schools, with a total of 2 210 reports (92.16%). And the majority of the outbreaks involved 10-29 incident cases. The dominant isolated virus strains for the outbreaks were influenza B (1 505 outbreaks, 62.76% of all the outbreaks). Conclusion: Seasonality of influenza outbreaks were observed in mainland China during 2017-2018 surveillance season and the reported influenza outbreaks were most frequently occurred in autumn-winter season and in southern China. Primary, secondary schools and nursery care schools are high-risk places for outbreaks, and the dominant isolated virus strains for the outbreaks were influenza B.