WHO tweaks Sars-CoV-2 variant tags, XBB.1.16 a VOI

The World Health Organization on Thursday said the Alpha, Beta, Gamma, Delta and Omicron parent lineage of Sars-CoV-2 are considered “previously circulating variants of concern ”, while XBB.1.5 is a variant of interest, as it updated its tracking system and working definitions to better correspond to the current global variant landscape. The Omicron viruses account for over 98% of the publicly available sequences since February 2022 and constitute the genetic background from which new Sars-CoV-2 variants will likely emerge, although the emergence of variants derived from previously circulating VOCs or of completely new variants remains possible. “Based on comparisons of antigenic cross reactivity using animal sera, replication studies in experimental models of the human respiratory tract, and evidence from clinical and epidemiological studies in humans, there is consensus among experts in WHO’s Technical Advisory Group on Sars-CoV-2 Virus Evolution that compared to previous variants, Omicron represents the most divergent VOC seen to date,” the WHO said in a statement. Therefore, from March 15, 2023, the WHO variant tracking system will consider the classification of Omicron sub-lineages independently as variants under monitoring, VOIs, or VOCs,” it said.