Data from: Global circulation patterns of seasonal influenza viruses vary with antigenic drift

Understanding the spatio-temporal patterns of emergence and circulation of new human seasonal influenza virus variants is a key scientific and public health challenge. The global circulation patterns of influenza A/H3N2 viruses are well-characterized but the patterns of A/H1N1 and B viruses have remained largely unexplored. Here, based on analyses of 9,604 hemagglutinin sequences of human seasonal influenza viruses from 2000–2012, we show that the global circulation patterns of A/H1N1 (up to 2009), B/Victoria, and B/Yamagata viruses differ substantially from those of A/H3N2 viruses. While genetic variants of A/H3N2 viruses did not persist locally between epidemics and were reseeded from East and Southeast (E-SE) Asia, genetic variants of A/H1N1 and B viruses persisted across multiple seasons and exhibited complex global dynamics with E-SE Asia playing a limited role in disseminating new variants. The less frequent global movement of influenza A/H1N1 and B viruses coincided with slower rates of antigenic evolution, lower ages of infection, and smaller less frequent epidemics compared to A/H3N2 viruses. Detailed epidemic models support differences in age of infection, combined with the less frequent travel of children, as likely drivers of the differences in the patterns of global circulation, suggesting a complex interaction between virus evolution, epidemiology and human behavior.

解析新型人类季节性流感病毒变异株的出现与传播的时空模式，是当前科学研究与公共卫生领域的核心挑战之一。目前甲型流感病毒A/H3N2亚型的全球传播模式已得到充分阐明，但甲型A/H1N1亚型与乙型（B型）流感病毒的传播模式仍未得到充分探索。本研究基于2000至2012年间收集的9604条人类季节性流感病毒血凝素（hemagglutinin）序列开展分析，结果显示，甲型A/H1N1（截至2009年）、B/Victoria系与B/Yamagata系流感病毒的全球传播模式，与甲型A/H3N2亚型存在显著差异。甲型A/H3N2亚型的基因变异株无法在两次流行季之间于本地持续留存，需依赖东亚与东南亚（E-SE）地区反复输入；而甲型A/H1N1与乙型流感病毒的基因变异株则可跨多个流行季持续存在，其全球传播动态更为复杂，东亚及东南亚地区在新型变异株的传播扩散中仅发挥有限作用。相较于甲型A/H3N2亚型，甲型A/H1N1与乙型流感病毒的全球跨区域传播频率更低，这与其抗原进化速率更缓、感染人群年龄更低、流行规模更小且暴发频率更低的特征相契合。精细化流行模型分析表明，感染年龄的差异结合儿童出行频率更低的因素，可能是导致两类病毒全球传播模式差异的关键驱动因素，这也揭示了病毒进化、流行病学特征与人类行为之间存在复杂的相互作用。