Analysis on influenza surveillance in Chaoyang district, Beijing, 2013−2022

  Objective  To analyze the etiological characteristics and incidence trend of influenza in Chaoyang district of Beijing and provide scientific reference for influenza prevention and control.

  Methods  Nucleic acid testing was performed by using the throat swabs from influenza-like illness (ILI) cases submitted to Chaoyang District Center for Disease Control and Prevention, and the data of influenza surveillance in Chaoyang were analyzed by statistical method.

  Results  A total of 27928 samples of ILI cases were collected, and 4415 positive samples were detected, the positive rate of influenza virus nucleic acid was 15.81%, The positive peak of influenza virus nucleic acid detection was mainly in winter and spring, and different subtype viruses circulated alternately. The differences in positive rate of influenza virus nucleic acid detection in different seasons were significant (χ²=3698.274, P<0.001), Influenza A (H1N1) and (H3N2) viruses had the highest positive rates in winter (H1N1: χ²=1238.712, H3N2: χ²= 1317.144, P＜0.001). The positive rates of influenza B viruses Victoria and Yamagata linages were significantly higher in winter and spring than in summer and autumn (χ²=1526.712, P＜0.001). The differences in positive rates among different age groups were significant (P<0. 001), and the positive rate in age group 25−59 years was highest (21.13% ). There was no significant difference in the positive rate between men and women (χ²=1.455, P=0.228).

  Conclusion  The positive peak of influenza virus nucleic acid detection was mainly in winter and spring, and different subtype viruses circulated alternately in Chaoyang. It is necessary to further strengthen the surveillance and early warning of influenza, pay attention to the changes of the predominant strains of influenza viruses, continue to promote the influenza vaccination, explore various prevention and control measures, and reduce the additional impact of COVID-19 on influenza.