Since 1 January 2012, influenza A(H1N1)pdm09, influenza A(H3N2) and influenza B/Victoria and B/Yamagata lineage viruses have been detected and analysed in EU/EEA countries. The report summarises the findings as follows:

• Type A viruses have predominated over type B.
• A(H3N2) viruses have predominated over A(H1N1)pdm09 viruses.
• A(H1N1)pdm09 viruses continue to show genetic drift from the vaccine virus, A/California/07/2009, but the vast majority remain antigenically similar to it.
• During the last nine months, all European A(H3N2) viruses sequenced fell within five genetic clusters.
• Recent B/Victoria lineage viruses fell within the B/Brisbane/60/2008 genetic clade and were antigenically similar to reference cell-propagated viruses of the B/Brisbane/60/2008 genetic clade.
• Recent B/Yamagata-lineage viruses fell into two genetic clades, represented by the recommended vaccine component for the 2012/2013 influenza season, B/Wisconsin/1/2010 (clade 3), or B/Estonia/55669/2012 (clade 2); viruses in these clades are antigenically distinguishable.
• Antigenic analyses of A(H3N2)v viruses, the cause of zoonotic infections in the USA, indicate that these viruses are antigenically distinct from seasonal A(H3N2) viruses.

For further details, please download the complete report 'Influenza virus characterisation - Summary Europe, September 2012'

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Seasonal influenza health topic