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 pandemic’s 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.

中文翻译：

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COVID-19 大流行干预措施重塑了季节性流感病毒的全球传播


季节性流感病毒的全球动态为监测、干预和疫苗接种策略的设计提供了信息。COVID-19 大流行提供了一个独特的机会来评估全球流感传播如何受到人类行为变化的干扰。我们结合了分子、流行病学和国际旅行数据，发现大流行的爆发导致国际流感谱系运动的强度和结构发生变化。在大流行期间，南亚作为甲型流感病毒的系统发育主干位置发挥了重要作用，而西亚维持了乙型/维多利亚流感的传播。我们探讨了整个大流行期间流感谱系动态的驱动因素以及 B/Yamagata 谱系可能灭绝的原因。3 年后，除 B/Yamagata 外，区域间流感谱系移动的强度恢复到大流行前的水平，在全球空中交通恢复后，突出了全球谱系传播模式对实质性扰动的稳健性。