New COVID variant Mu added to WHO’s watchlist

The group added Mu, formally known as B.1.621, to its list of variants of interest on Aug. 30. Mu is already spreading in the U.S. and has been here for over a month.

WHO says Mu has genetic mutations that indicate resistance to natural immunity and the vaccines that have been approved so far. Health officials called for further study to determine if the variant is more contagious or more deadly than other COVID mutations.

Mu seems to have originated in Colombia in January and has been most prevalent so far in Florida, specifically the Miami area, perhaps due to frequent travel between those areas.

The mutation still accounts for a fraction of overall cases globally, but WHO officials say it is important to keep an eye on.

“Although the global prevalence of the Mu variant among sequenced cases has declined and is currently below 0.1%, the prevalence in Colombia (39%) and Ecuador (13%) has consistently increased,” said WHO in its weekly COVID epidemiological report.

The Centers for Disease Control and Prevention has also declared Mu a variant of interest, but has not yet moved it to the level of variant of concern, which indicates “a significant impact on transmissibility, severity and/or immunity.” The European Center for Disease Control and Prevention also notes it could have significant impact, but cautions that right now data is preliminary.

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