What is the Mu variant of Covid-19 and where has it been seen?

The Mu variant, or technically B.1.621, first appeared in Columbia in January

As the delta variant continues to make headlines as it sweeps the nation, health officials are watching another variant on the horizon.

Dr Anthony Fauci, the US’s leading infectious disease expert, said while there are cases of the Mu variant in the US, it’s not the dominant variant.

"We’re keeping a very close eye on it. It is really seen here, but it is not at all even close to being dominant," Mr Fauci said on Thursday during a White House Covid response news briefing.

There are 2,000 cases of the Mu variant in the US as of Friday, according to the Global Initiative on Sharing All Influenza Data.

"We’re paying attention to it, we take everything like that seriously, but we don’t consider it an immediate threat right now,” Mr Fauci said.

Mr Fauci is watching out for the Mu variant because lab data says “it would evade certain antibodies.” But that hasn’t been proven in a clinical setting.

This week, the World Health Organization deemed Mu a “variant of interest,” saying it can potentially elude immunity granted from a previous Covid-19 infection or the vaccine.

The Mu variant, or technically B.1.621, first appeared in Columbia in January. A Columbian health official said the variant was responsible for the third surge that occurred from April to June.

"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," the WHO said.

It has also been spotted in South Korea, officials announced on Friday. The three infections are in people who have traveled from Mexico, the US, and Columbia.

The Centers for Diseases Control and Prevention has yet to call Mu a variant of concern. As of right now, there are four concerning variants on the organization’s list: Alpha, Beta, Gamma, and Delta.