Abstract: Objective To analyze the epidemiological and etiological characteristics of influenza in Taishan District of Tai'an City from 2017 to 2023,so as to provide evidence for formulating prevention and treatment strategies. Methods Descriptive epidemiological analysis was used to analyze the data of influenza in Tai'an City from 2017 to 2023,which was reported in China Disease Prevention and Control information system. Results From 2017 to 2023,a total of 3 903 cases of influenza were reported in Taishan District,with an average annual incidence of 73.68/100 000. The age group <15 years old accounted for 71.84% of the reported cases,mainly students,scattered children and kindergarten children. The top three months with the number of cases from 2017 to 2023 were December（32.03%）,March（24.86%）,and November（10.36%）. From 2017 to 2019 and 2021,there was a single peak distribution in winter and spring,there were no epidemic peak in 2020 and 2022,in 2023,there were two epidemic peaks in February to May,September to December. From 2017 to 2023,4 756 influenza like cases underwent pathogen testing,with 868 positive cases and a positivity rate of 18.25%. Among them,344 cases（39.63%） were seasonal H3N2 type,accounting for the highest proportion, followed by 237 cases（27.30%） of new A H1N1 type,193 cases（22.24%） of Victoria type B,and 94 cases（10.83%） of Yamagata type B. From 2017 to 2023,a total of 23 influenza epidemics were reported in Taishan District,of which 11 cases were in primary schools（47.85%）,accounting for the highest proportion,and 18 were in primary and secondary schools and kindergartens（78.26%）. The pathogen types of influenza epidemics reported in each year were consistent with the detection of influenza-like cases in sentinel hospitals. Conclusion The average annual reported incidence of influenza in Taishan District from 2017 to 2023 was 73.68/100 000. The reported incidence rate in urban areas was higher than that in rural areas. The incidence was mainly in the age group under 15 years old,with obvious seasonality. The number of cases was the highest in December and March. In 2023,there were two epidemic peaks in spring and winter,the epidemic intensity was significantly higher than that in previous years,and seasonal H3N2（39.63%） and new A H1N1（27.30%） were the dominant strains. Different pathogenic types could spread simultaneously or alternatively in epidemic season. The influenza epidemic mainly occurred in schools and kindergartens,and efforts should be made to strengthen pathogen monitoring and influenza prevention and control in kindergartens,primary and secondary schools.

Key words: Influenza, Epidemiological characteristics, Etiological characteristics, Influenza-like cases, Influenza epidemic