Epidemiological Dynamics and Phylogeography of Influenza Virus in Southern China

Abstract

We propose that novel influenza viruses emerge and evolve in multiple geographic localities and that the global evolution of influenza virus is complex and does not simply originate from a southern Chinese epicenter.

Differing Epidemiological Dynamics of Influenza B Virus Lineages in Guangzhou, Southern China, 2009-2010

“…In line with our results from Guangzhou, short-term persistence of influenza B viruses was reported in another large subtropical city of southern China, Shenzhen (20). Like Shenzhen, Guangzhou hosts a large number of migrant workers who come to work in Guangzhou in spring and return to their hometowns in winter before the Chinese New Year.…”

“…There was also evidence of intra-and interlineage reassortment events. Finally, phylogenetic clustering methods (20,(40)(41)(42)(43)(44). In line with these findings, our 2-year study in Guangzhou City reveals multiple introductions of influenza B viruses from other Chinese cities and from abroad.…”

“…Since the vaccine also contains antigens for influenza A viruses, the optimal vaccine strategy also depends on the timing of influenza A virus activity. While we do not have any information on the seasonality of influenza A virus circulation in Guangzhou, other Southern Chinese cities experience influenza A virus activity in late spring, which would justify the suggested vaccine strategy (20,47,48). Although the emergence of the A/H1N1 pandemic virus in 2009 could have affected the seasonality of influenza B virus circulation in our Guangzhou study, past laboratory surveillance data suggest that seasonal influenza virus typically circulates in warmer months in this region (20,47,48).…”

“…The Victoria lineage is thought to have re-emerged in North America and Europe and spread worldwide around 2000 to 2002 (9,14,15). In China, both the Victoria and Yamagata lineages have been cocirculating for a substantial period of time (16)(17)(18)(19)(20), with more frequent dominance of the Yamagata lineage in the 1990s, especially in northern China (21,22). In contrast, during 2004 to 2008, Victoria strains became widespread in China, including in Zhejiang province, in Hunan province, and in Beijing (17,19,(23)(24)(25).…”

“…For example, during 2003 to 2008, excessive mortality attributable to influenza B virus infections was estimated to be higher than that attributable to seasonal A/H3N2 or A/H1N1 virus in China (28). Influenza B virus has caused more hospitalizations than influenza A virus in postpandemic H1N1/09 seasons (20). Influenza B virus infections also caused around one-quarter of influenza-associated hospitalizations in Hong Kong during 2000 to 2010 and were responsible for the major proportion of influenza burden in Taiwan during 2004 to 2012 (26,27).…”