/The phylogenetic tree for the HA genomic sequences of representative influenza B (Victoria clade) viruses collected since 2023 was constructed. Strains were color-coded according to their antigenic clusters. As depicted in Figure S6, viruses within the clade V1A.3a.2 were categorized under the antigenic cluster AU21. Notably, all viruses collected in the last half year were associated with the AU21 cluster.