The Global Circulation of Seasonal Influenza A (H3N2) Viruses
Colin A. Russell,1 Terry C. Jones,1,2,3 Ian G. Barr,4 Nancy J. Cox,5 Rebecca J. Garten,5 Vicky Gregory,6 Ian D. Gust,4 Alan W. Hampson,4 Alan J. Hay,6 Aeron C. Hurt,4 Jan C. de Jong,2 Anne Kelso,4 Alexander I. Klimov,5 Tsutomu Kageyama,7 Naomi Komadina,4 Alan S. Lapedes,8 Yi P. Lin,6 Ana Mosterin,1,3 Masatsugu Obuchi,7 Takato Odagiri,7 Albert D. M. E. Osterhaus,2 Guus F. Rimmelzwaan,2 Michael W. Shaw,5 Eugene Skepner,1 Klaus Stohr,9 Masato Tashiro,7 Ron A. M. Fouchier,2 Derek J. Smith1,2*
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.
1 Department of Zoology, University of Cambridge, Cambridge, UK.
2 Department of Virology, Erasmus Medical Centre, Rotterdam, Netherlands.
3 Universitat Pompeu Fabra, Barcelona, Spain.
4 World Health Organization (WHO) Collaborating Centre for Reference and Research on Influenza, Melbourne, Australia.
5 WHO Collaborating Center for Influenza, Centers for Disease Control and Prevention, Atlanta, GA, USA.
6 WHO Collaborating Centre for Influenza, National Institute for Medical Research (NIMR), London, UK.
7 WHO Collaborating Center for Influenza, National Institute for Infectious Diseases, Tokyo, Japan.
8 Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
9 Novartis Vaccines and Diagnostics, Cambridge, MA, USA.