Background: The live bird markets in the core area of the migratory bird migration base (Poyang Lake) are monitored for long-term avian influenza. The spatial and temporal patterns of avian influenza were analysed, along with the impact of the COVID-19 pandemic and vaccination.

Methods: Real-time reverse transcription polymerase chain reaction was used to test samples for general positivity of type A influenza and to detect H5, H7, and H9 subtypes to differentiate between various subtypes. The Cochran-Armitage test was applied to analyse trends in avian influenza changes, while STL and rwdrift models were used for seasonal analysis and predicting future positivity rates.

Results: A total of 2,421 avian influenza samples were collected, with a positivity rate of 75.1%. The quarterly positivity rates were all greater than 70%. Since 2016, the overall avian influenza positivity rate in urban core areas has consistently been higher than that in county seats, showing an upward trend. Among the samples, the cutting board samples had the highest positivity rate (86.7%), whereas the faecal samples had the lowest positivity rate (67.8%). The overall positivity rate of avian influenza in the post-COVID-19 period (83.0%) was significantly higher than that in the pre-COVID-19 period (65.7%). Following vaccination, the positivity rate of the H7 subtype of avian influenza virus dropped from 10.4% to 0.

Conclusions: Avian influenza positivity rate in the core areas of Poyang Lake is among the highest nationwide and exhibits seasonal patterns (higher in winter and spring). The cutting board samples had the highest positivity rate, highlighting the importance of timely cleaning of cutting boards to control the spread of avian influenza. After the COVID-19 pandemic, the avian influenza positivity rate increased significantly, with a particularly notable rise in the H5 subtype, which aligns with the global trend of increased H5 prevalence. After vaccination, the H7 subtype completely disappeared, but the impact on the H5 subtype was minimal. The predictive results indicate that avian influenza in this region will continue to rise and remain at high levels. We recommend strengthening avian influenza monitoring in this area and promptly implementing disinfection and cleaning measures in market environments to prevent future outbreaks.