Where Mu Originated As Scientists Keep Close Eye on Mutated COVID Variant

Researchers are keeping an eye on the Mu variant of COVID which has been in the U.S. for several months. The variant, also known as B.1.621, was designated as a Variant of Interest (VOI) by the World Health Organization on August 30 this year.

Since then it has made numerous headlines with cases reported in every U.S. state except for Nebraska, according to Outbreak.info, which collects virus sequencing data from the GISAID database.

Mu was first documented in Colombia in January this year, according to the WHO. Since then, outbreaks have occurred in other countries including nations from South America and Europe.

In a weekly epidemiological update on August 31, the WHO said more than 4,500 sequences of Mu had been uploaded to GISAID from 39 countries as of August 29.

The variant was particularly prevalent in Colombia and Ecuador, where its prevalence was 39 percent and 13 percent respectively, at that time.

Since then, Outbreak.info reports the global number of sequences has increased to 5,309 as of September 8, with 2,314 of those in the U.S.

This may be an increase, though the variant makes up only a tiny proportion of U.S. COVID samples, according to Centers for Disease Control and Prevention (CDC) data.

The data shows that, in the week ending September 4, Mu accounted for just 0.1 percent of COVID samples sequenced. The much more widespread Delta variant, on the other hand, accounted for around 99 percent of samples.

According to existing data on Mu, researchers think the variant may pose some resistance to vaccines and natural antibodies, based on the mutations it has.

Francesca Beaudoin, interim chair of epidemiology at the Brown University School of Public Health, told Newsweek earlier this month: "The combination of mutations is causing concern that this version of the virus may be able to evade our immune system, particularly antibody defenses.

"This could mean that vaccination is less protective against this variant and that other treatments (monoclonal antibodies) are less effective, but these theories still need to be tested."

In a press briefing on September 2, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), said the variant had mutations that "suggests that it would evade certain antibodies… but there isn't a lot of clinical data to suggest that.

"Bottom line: We're paying attention to it. We take everything like that seriously. But we don't consider it an immediate threat right now."

COVID sample
A stock photo shows a lab technician working with a COVID sample. Thousands of sequences with the Mu variant have been detected worldwide since it was first identified. mbz-photodesign/Getty