- Chen, Zhiyuan;
- Tsui, Joseph;
- Gutierrez, Bernardo;
- Busch Moreno, Simon;
- du Plessis, Louis;
- Deng, Xiaowei;
- Cai, Jun;
- Bajaj, Sumali;
- Suchard, Marc;
- Pybus, Oliver;
- Lemey, Philippe;
- Kraemer, Moritz;
- Yu, Hongjie
The global dynamics of seasonal influenza viruses inform the design of surveillance, intervention, and vaccination strategies. The COVID-19 pandemic provided a singular opportunity to evaluate how influenza circulation worldwide was perturbed by human behavioral changes. We combine molecular, epidemiological, and international travel data and find that the pandemics onset led to a shift in the intensity and structure of international influenza lineage movement. During the pandemic, South Asia played an important role as a phylogenetic trunk location of influenza A viruses, whereas West Asia maintained the circulation of influenza B/Victoria. We explore drivers of influenza lineage dynamics across the pandemic period and reasons for the possible extinction of the B/Yamagata lineage. After a period of 3 years, the intensity of among-region influenza lineage movements returned to pre-pandemic levels, with the exception of B/Yamagata, after the recovery of global air traffic, highlighting the robustness of global lineage dispersal patterns to substantial perturbation.