Characterization of Omicron XBB subvariants in Vietnam

SARS-CoV-2, an RNA virus that causes COVID-19, is known for its high mutation rate. Its latest variant, Omicron, has raised concerns due to several amino acid substitutions in the spike protein that could increase its transmissibility and virulence. Omicron has also produced subvariants with specific nucleotide mutations to evade antibodies and enhance infectivity. One of these subvariants, XBB, has become prevalent in Vietnam. Therefore, it is essential to accurately assess the genetic diversity of this emerging variant. This study analyzed the April 15th, 2023 updated data and identified nine XBB and subvariants in Vietnam, with XBB.1.5 being the most common. Phylogenetic analysis revealed that the original XBB variant was related to BA.2.75, and XBB.1.5 had a close relationship with XBB.1.2. A crucial mutation, G22317T (G252V), played an essential role in the emergence of the XBB subvariant, and XBB.1.5 split from XBB.1.2 with an A22405T (E281D) mutation, as shown by the mutation network.