Influenza virus characterisation, summary Europe, July 2011

More specifically, Influenza A(H1N1)pdm, influenza A(H3N2), and influenza B/Victoria- and B/Yamagata-lineage viruses have been characterised genetically and antigenically. Some of the findings are:

• Recently isolated A(H1N1)pdm viruses continue to fall into several genetic groups but all groups show antigenic similarity to the currently recommended vaccine virus A/California/7/2009.
• A(H3N2) viruses fall into distinct genetic groups but there is no consistent correlation of altered antigenicity with any genetic group, compared with the vaccine virus A/Perth/16/2009.
• Influenza B viruses of the B/Victoria/2/87 lineage predominate over those of the B/Yamagata/16/88 lineage. Most of the B/Victoria/2/87 lineage viruses remain genetically and antigenically similar to the currently recommended vaccine virus B/Brisbane/60/2008.
• The majority of influenza B viruses of the B/Yamagata-lineage are in the B/Bangladesh/3333/2007 genetic clade but viruses received from three countries with Baltic coastlines fall within a different genetic clade.