Mu Now A COVID-19 ‘Variant Of Interest’: What You Should Know

ACROSS AMERICA — As the highly transmissible delta variant continues to drive a surge of COVID-19 infections across the United States, a new variant of interest is on the public health radar system.

The mu variant was added to the World Health Organization's list of “variants of interest” last week as the number of new daily COVID-19 cases in the United States topped 200,000 for the first time in months.

The WHO is currently monitoring four variants “of concern”: alpha, which was first detected in the United Kingdom; beta, first detected in South Africa; gamma, first detected in Brazil; and delta, which originated in India.

Should we be concerned about the mu variant? How effective are vaccines against it? Here are five things you should know:

1. Where did the mu variant originate?

The mu variant, also known as B.1.621, originated in Colombia, South America, in January.

The mu variant is among several on the WHO’s variants of interest list, meaning it may make vaccines and treatments less effective. Generally, more evidence is needed before public health officials elevate it to a variant of concern.

In addition to mu, the WHO is monitoring eta, a variant with cases documented in several countries; iota, which originated in the United States; kappa, which first emerged in India; and lambda, which originated in Peru.

2. Have there been any confirmed cases of the mu variant in the United States?

The mu variant was responsible for less than 0.1 percent of cases reported in the United States last week, according to data from the Centers for Disease Control and Prevention.

While the CDC does not document mu variant cases by state, at least one case reportedly has been confirmed in 49 states and the District of Columbia, according to a report by Newsweek.

California reportedly has the highest number of mu variant samples at 384 cases, Newsweek reported.

Outside of the United States, the mu variant accounts for fewer than 1 percent of COVID-19 cases globally, according to The Associated Press. In Colombia, it is likely responsible for about 39 percent of cases.

3. How does mu compare to the delta variant?

While the mu variant has been confirmed in dozens of countries, it doesn’t seem to be taking off like the delta variant, according to Maria Van Kerkhove with the WHO.

“The delta variant for me is the one that’s most concerning because of the increased transmissibility,” Kerkhove said during a news conference reported by CNBC.

To date, the delta variant remains the dominant variant in almost all of the 174 countries where it’s been detected, according to The AP. It currently makes up 98.8 percent of all cases in the United States.

4. Does the vaccine protect against the mu variant?

Many public health officials have said more real-world data is needed to determine whether the mu variant is more resistant to available vaccines.

Regardless, the vaccine remains the best line of defense against any COVID-19 variant.

“Variants are expected,” the CDC’s website states. “The best way to slow the emergence of new variants is to reduce the spread of infection by taking measures to protect yourself, including getting a COVID-19 vaccine when available.”

5. Should I be concerned?

To become a serious threat, any new variant has to compete with the “best of class.”

“Right now, that is delta,” Dr. Mike Ryan, head of the WHO’s health emergencies program, told CNBC, adding that the delta variant tends to “outcompete” other variants like mu.

This means the mu variant isn’t considered a threat, Dr. Anthony Fauci, the nation’s top infectious disease expert, said during a news conference last week.

“We’re paying attention to it, we take everything like that seriously, but we don’t consider it an immediate threat right now,” Fauci said, according to a CNBC report.