Objective   To analyze prevalence characteristics and variation trend of influenza in Guizhou province during 2011– 2021 and to provide evidences for influenza prevention and control.

  Methods   Throat swab specimens were collected from influenza-like illness (ILI) cases at fever/internal medicine and pediatric clinics of 13 national influenza sentinel surveillance hospitals in Guizhou province during 2011 – 2021 and detected with real-time reverse transcription-polymerase chain reaction (RT-PCR). Statistical analysis was conducted on the basis of annual influenza seasons.

  Results  Of the 135 537 specimens detected during the 10-year period, 16.73% (22 676) were positive for influenza virus nucleic acid. Among the positive specimens, the detection rate was the highest (34.3%) for subtype of H3N2 and the lowest (13.69%) for subtype of BY. Various viral subtypes were prevalent alternately during the period. Two prevalence peaks of influenza virus infection in winter-spring season and in summer season were observed, with slightly more infectious cases among females than among males and more cases among the people aged 5 – 24 years. There was a subtype-specific difference in the susceptibility of influenza virus in various populations and there was a significant difference in annual positive rate for the specimens detected.

  Conclusion  During 2011 – 2021 in Guizhou province, influenza was prevalence periodically with alternative prevalent viral subtypes; more influenza infections occurred in winter-spring and in summer seasons, especially among young people. The results suggest that surveillance and analysis on viral strain variation timely should be strengthened.