New coronavirus variant raising concern but not yet considered threat

While the Delta variant of the coronavirus accounts for 99 percent of current infections across the U.S., a new variant is getting the attention of public health experts.

The World Health Organization has called Mu, first identified in Colombia in January, a “variant of interest” that needs to be watched.

"It's in 39 countries. It's in 49 of the 50 states," Jessica Dixon, director of infection prevention at WakeMed, said Tuesday.

Still, Mu is responsible for only 0.2 percent of cases nationwide, Dixon said – only 2,000 or so total cases have been reported in the U.S. North Carolina doesn't report the Mu variant as part of its pandemic data collection, so it's unknown how many cases have occurred in the state.

White House coronavirus adviser Dr. Anthony Fauci said the variant is "not an immediate threat," and the Centers for Disease Control and Prevention haven't yet called it a variant of interest.

"We're keeping a very close eye on it. It is really seen here, but it is not at all close to being dominant," Fauci said.

But even with the scant data collected on Mu so far, it appears that the variant is highly contagious and may be more resistant to treatment than Delta and previous versions of the virus.

"It has a mutation that appears to potentially allow it to evade our treatment," Dixon said, referring to monoclonal antibodies and antiviral treatments.

"There's another mutation on this particular variant that suppresses your immune response, and that's really concerning," she said. "It can escape immunity, whether that's natural immunity or vaccine-mediated immunity."

Pfizer is studying the effect of its vaccine on the Mu variant.

Although Mu appears to be more deadly than the Delta variant, Dixon said, Delta appears to be keeping it from spreading.

"If there's anything good to be said about our current experience with Delta, it's that it does seem to be pushing out other variants at the moment. But we really just have to stay tuned and see where this goes," she said.

Vaccination is the best way to halt Mu altogether and prevent the virus from mutating further, Dixon said. Countries with higher vaccination rates have seen fewer mutations during the pandemic.

"The only way the virus can continue to mutate is for it to have hosts in which to live," she said. "Vaccination is absolutely our first line of defense and our best line of defense and our best [way] to get out of this pandemic."