RESUMO
@#Objective To understand the epidemiological and etiological characteristics of influenza in Mianyang City from 2019 to 2021, so as to provide a basis for the prevention and control of influenza. Methods Influenza surveillance data in Mianyang City from 2019 to 2021 were collected and analyzed statistically. Results A total of 55 970 cases of influenza were reported in Mianyang City from 2019 to 2021, with an average annual incidence of 388.08/100 000. A total of 103 723 cases of influenza -like illness cases (ILI) were reported, with an average annual ILI% of 3.58%. The incidence, ILI% , and positive detection rates of influenza were all far higher than those in the corresponding period in 2019. The classification of the population is mainly composed of students under the age of 15. The top three reported cases were Fucheng District (20 118, 35.94%), Youxian District (6 394, 11.42%) and Jiangyou District (5 800, 10.36%). 10 126 samples of ILI were received and detected, with a positive rate of 19.53%, the positive rate of ILI samples was mainly students under 15 years old. The dominant strains of influenza viruses showed an alternating trend over the years, and A (H3) was the predominant type in 2019. Except for 2 A (H9) strains detected in 2021, the rest were all BV strains. Due to the impact of COVID-19 in 2020, the positive detection rate was low throughout the year. 43 outbreaks of ILI were reported, which were mainly occurred in winter, and most of them were in primary schools. Conclusion From 2019 to 2021, the characteristics of cases, ILI, pathogen surveillance and outbreak events of influenza in Mianyang City are basically the same, with students under 15 years of age and schools remaining the key population and sites of concern. the importance of non-pharmaceutical interventions for influenza prevention and control is further evidenced by the low incidence of influenza during the COVID-19 pandemic.
