BW.1 is the new more transmissible and immune evasive SARS-CoV-2 variant


Scientists from the Instituto de Biotecnología – Mexico, Universidad Autónoma de la Ciudad de México, Instituto Mexicano del Seguro Social and MIVEGEC, Université de Montpellier, IRD, CNRS are warning that a new SARS-CoV-2 variant called BW.1 is spreading rapidly in Mexico and is likely to spread across to the United States, Canada and also elsewhere due to lack of proper border health screenings.

The BW.1 variant also known as B.1.1.529. originated from the BA.5 variant.*

The study findings showed BW.1 appears to have arisen in the Yucatan Peninsula in Mexico sometime around July 2022 during the fifth COVID-19 wave. Its explosive growth may be in part explained by relevant escape mutations also found in BQ.1.
The study findings were published on a preprint server and are currently being peer reviewed.

The coordinated effort on Mexican genomic surveillance of SARS-CoV-2 has identified and characterized BW.1, a novel variant with four prominent RBD key mutations S:L452R, S:F486V, S:K444T, S:N460K, the same that provide BQ.1 and its descendants with enhanced infectious and immune evasion capabilities.

BW.1 appears to have originated from Mexican BA.5.6.2 variants in Yucatan (a buoyant international tourist destination), as these parental variants had already diverged from BA.5.6.2 variants from the rest of the world and inherited their genomic composition vertically to BW.1.

The incorporation of mutations S:N460K and ORF1a:V627I kickstarted BW.1 into a distinct clade, which has since been detected in other countries but has yet to demonstrate it might compete with current dominating variants in other parts of the workd.

In Mexico, however, BW.1 emerged during the previous epidemiological surge and has since become a major player in the Yucatan Peninsula, where cases have begun to increase once more.

Only time will tell if its advance may be halted by the arrival of variants in the BQ.x lineage that have become the major driving force of the pandemic in recent weeks.


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