We previously highlighted our projections for the coming influenza season in North America, emphasizing the unknown represented by rapidly emerging type A/H3N2 variant. CDC's first substantive report on the 2012-2013 influenza season provides the first hint: that no A/H3N2 variant has been found in routine isolates (i.e. those not associated with investigation of agricultural fairs), and a reminder that isolates of A/H1N1 and A/H3N2 analyzed over the summer are well matched to the recommended 2012-2013 vaccine strain. The key take-home point is the emphasis that testing has only just begun for the formal "influenza season", hence "no antigenic characterization data is available for specimens collected after October 1, 2012."
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