The Global Circulation of Seasonal Influenza A (H3N2) Viruses

Department of Zoology, University of Cambridge, Cambridge, UK.
Science (Impact Factor: 33.61). 05/2008; 320(5874):340-6. DOI: 10.1126/science.1154137
Source: PubMed


Antigenic and genetic analysis of the hemagglutinin of ∼13,000 human influenza A (H3N2) viruses from six continents during
2002–2007 revealed that there was continuous circulation in east and Southeast Asia (E-SE Asia) via a region-wide network
of temporally overlapping epidemics and that epidemics in the temperate regions were seeded from this network each year. Seed
strains generally first reached Oceania, North America, and Europe, and later South America. This evidence suggests that once
A (H3N2) viruses leave E-SE Asia, they are unlikely to contribute to long-term viral evolution. If the trends observed during
this period are an accurate representation of overall patterns of spread, then the antigenic characteristics of A (H3N2) viruses
outside E-SE Asia may be forecast each year based on surveillance within E-SE Asia, with consequent improvements to vaccine
strain selection.

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Available from: Masato Tashiro
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    • "Influenza A virus infection is a major global health challenge [1,2]. Although the virus infects people of all ages, elderly individuals (>75 years old) have more than 10-fold higher influenza-associated hospitalization and higher mortality compared to other age groups [3]. "
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    • "In addition to the above-mentioned evidence for the scenario ― a new viral variant emerged from East and Southeast Asia (E-SE Asia) during the 2009 season ― several studies have shown that seasonal influenza epidemics are usually seeded from E-SE Asia or China [12,13]. Fluctrl thus provides a functionality for limiting the scope of analyzed human influenza data to E-SE Asia by constraining the latitude (between −8 and 8) and the longitude (between 70 and 150) that were extracted from strain information. "
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