Epidemiological characteristics of influenza infection in visiting patients of a tertiary TCM hospital in Beijing from 2019 to 2023

XIN Ran; NIU Yanlin; Xuan Yabo

doi:10.3969/j.issn.1007-8134.2025.05.013

Abstract：Objective To delineate and interpret the epidemiological characteristics of influenza infection in outpatients,emergency patients,and inpatients in a tertiary Traditional Chinese Medicine(TCM)hospital.Methods The influenza virus(IFV)nucleic acid test results of outpatients,emergency,and hospitalized patients in a tertiary TCM hospital from Jan.2019 to Dec.2023 were collected,of which the epidemical distribution was described and the difference was compared by Runs test.Results Nineteen thousand six hundred forty-five outpatients,emergency patients,and inpatients were included in the study,and the total positive rates was 19.82%.Compared to 2019(16.96%),test positive rates of IFV decreased during 2020-2022(5.88%、1.99%、5.51%),and then it surged again in 2023(22.74%),exceeding historical levels(P<0.05).There are one incidence peak in 2019(P<0.05)and 2 in 2023(P<0.05),and were no significant clustering observed during 2020-2022.The positive rates were highest in age groups≥60 years(64.10%、58.54%、70.83%、37.74%),and in hospitalized patients(82.91%、70.73%、83.33%、45.28%)from 2019 to 2022.During 2023 the proportion of infections in age groups 25、59 years(47.01%)and in urgent care patients(65.86%)increased.IFV was mainly isolated among hospitalized patients in respiratory,nephrology and orthopedic ward,and among outpatients in fever clinic,pediatric and respiratory clinic.Influenza A(95.80%、88.37%、55.17%、94.45%)was the predominant type of IFV detected during 2019-2021,2023,while influenza B(60.00%)was the main type detected in 2022(P<0.05).Conclusion The IFV positive rates was rather lower during 2020-2022 and returned to higher in 2023 with 2 peaks.There are differences in the population distribution between the 2 intervals.Subtype A is the predominant strain of influenza virus.