Molecular Epidemiology and Genetic Diversity of Influenza B Viruses Based on Whole‐Genome Analysis in Japan and Myanmar, 2016–2020

This study reveals synchronized lineage shifts, inter-lineage reassortment, and vaccine mismatches of IBVs in two distinct countries. The disappearance of B/Yamagata and emergence of divergent B/Victoria clades highlight the need for sustained molecular surveillance to guide vaccine strain selection.