Inter-Seasonal Influenza is Characterized by Extended Virus Transmission and Persistence

摘要: The factors that determine the characteristic seasonality of influenza remain enigmatic. Current models predict occurrences outside normal surveillance season within a temperate region largely reflect importation viruses from alternate hemisphere or equatorial regions in Asia. To help reveal drivers we investigated origins and evolution sampled during inter-seasonal periods Australia. this end conducted an expansive phylogenetic analysis 9912, 3804, 3941 hemagglutinnin (HA) sequences A/H1N1pdm, A/H3N2, B, respectively, collected globally period 2009-2014. Of 1475 Australia, 396 (26.8% Australian, 2.2% global set) were monitored (1 May – 31 October). Notably, rather than simply reflecting short-lived importations virus localities with higher prevalence, documented variety more complex transmission patterns including “stragglers” preceding “heralds” forthcoming season, which included clearly We also provide evidence for persistence B between epidemic seasons, viral lineage begins one continues throughout into following season. Strikingly, disproportionately high number events occurred tropical subtropical providing further climate plays important role shaping seasonality.