Figure 1.

Phylogenetic analyses. The nomenclature of influenza viruses is defined according to type (e.g., A), place of origin (e.g., Paris), strain number (e.g., 664), and year of isolation (e.g., 2015). The strains in red and black correspond respectively to the vaccine strains and to the reference strains. Nucleotide sequences were aligned to A (H3N2) reference strains. The virus (in light blue) was found to belong to the 3C.2a clade, the most frequent of the H3N2 strains circulating during the winter of 2014–2015.