Epidemic trends and prevention and control of seasonal influenza in China after the COVID-19 pandemic

During the COVID-19 pandemic, a series of non-pharmaceutical interventions, which were implemented to curb the spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), significantly modified the seasonal pattern of influenza. The intensity of influenza activity markedly decreased and B/Yamagata lineage was no longer detected. As the national influenza sentinel surveillance data shown, clear seasonal patterns were observed for influenza between 2012-2019, annually with an average of 14.57% of specimens tested positive for influenza virus. However, the seasonal pattern of influenza was disrupted after the outbreak of COVID-19. In the 2020-2021 season, influenza demonstrated an extremely low activity (yearly positivity rate