What is the COVID-19 mu variant?

A new coronavirus variant designated as mu by the World Health Organization is being monitored as a "variant of interest."


A new coronavirus variant designated as mu by the World Health Organization is being monitored as a "variant of interest," but federal health officials say they don't consider it immediately dangerous.

Last week, the WHO designated the B.1.621 variant as a "variant of interest" because it carries mutations that could help it partially evade vaccines and treatments such as monoclonal antibodies. WHO named it mu under its system to designate important variants using the Greek alphabet.

"This variant has a constellation of mutations that suggests that it would evade certain antibodies," Dr. Anthony Fauci said Thursday of mu. "Not only monoclonal antibodies, but vaccine and convalescent serum-induced antibodies. But there isn't a lot of clinical data to suggest that — it is mostly laboratory, in vitro, data.

"Not to downplay it — we take it very seriously. But remember, even when you have variants that do diminish somewhat the efficacy of vaccines, the vaccines still are quite effective against variants of that type. 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," he said.

Dr. Jason Salemi, an epidemiologist with the University of South Florida told sister station WESH that until a greater percentage of the population is vaccinated, it is inevitable that new variants of COVID-19 will develop.

But he said with the delta variant making up 99% of the cases in the U.S. right now, that's what people should be concerned with.

"I'm not at all worried about mu or lambda right now, I continue to be worried about delta," he said.

Salemi said reports of mu should encourage more vaccinations.

"It underscores the importance of vaccinations and other mitigation efforts because the more that we let the virus persist at high levels, the higher the likelihood that new variants will emerge and become as problematic as delta," he said.

As for whether current vaccines would be effective against the mu variant, he said the evidence indicates they will.

"Right now there's no reason to believe that vaccination wouldn't offer a very significant risk reduction in terms of your likelihood of severe disease. But again that's something we will continue to monitor," Salemi said.