Epidemiological characteristics of influenza in Yuhang District / 预防医学

ABSTRACT

Objective@#To investigate the epidemiological characteristics of influenza in Yuhang District, Hangzhou City from 2019 to 2023, so as to provide the reference for formulating influenza prevention and control measures.@*Methods@#Influenza case data with current address in Yuhang District was collected through the Chinese Disease Prevention and Control Information System from 2019 to 2023. Influenza-like illness data was collected through the Hangzhou Epidemiological Investigation System. Time distribution, population distribution and pathogen detection of influenza-like illness were descriptively analyzed.@*Results@#There were 118 319 influenza cases reported in Yuhang District from 2019 to 2023, with an average annual reported incidence rate of 2 316.80/105. The highest incidence rate was seen in 2023, with a reported incidence rate of 5 736.82/105. The peak incidence of influenza occurred from November to March of the following year, presenting the winter and spring epidemic. The cases were mainly distributed in the age groups of 7 to 14 years and 25 to 59 years, with 31 310 and 34 470 cases, accounting for 26.46% and 29.13%, respectively. Influenza cases were reported in all 12 towns (streets) in Yuhang District, with the top two being Wuchang Street and Liangzhu Street, with the average annual incidence rates of 17 346.08/105 and 14 945.80/105, respectively. From 2019 to 2023, there were 103 868 cases of influenza-like illness, and 1 482 throat swab samples were collected. Among them, 260 positive samples of influenza virus were detected, with a positive rate of 17.54%. The peak detection period for positive specimens was from November to March of the following year, with 222 influenza virus positive specimens detected. The influenza virus types included H1N1, H3N2, and Victoria B, accounting for 25.77%, 38.85% and 35.38%, respectively.@*Conclusions@#The peak of influenza outbreak in Yuhang District from 2019 to 2023 was in winter and spring, with children and adolescents being the main affected objectives. H1N1, H3N2 and Victoria B were alternately prevalent. Prevention and control measures such as influenza vaccination should be strengthened.