Fig. 3
From: Epidemiological and virological surveillance of influenza viruses in China during 2020–2021
Phylogenic tree of the HA gene of the global B/Victoria lineage viruses from 2020 to 2021. A HA phylogenic tree of all sequence. B HA phylogenic tree of Subgroup 1A.3a.2. HA sequences after removing duplicates and incomplete coding regions, a total of 5046 sequences were used, including 1137 sequences in the mainland of China. The red bar denotes the distribution of viruses collection months. Asia countries excludes the mainland of China