Sep 30, 2021, 12:46:25 PM CDT Dec 21, 2021, 2:10:17 PM CST

5 FAQs about the COVID-19 Mu variant

An infectious disease expert shares the latest information about the new COVID-19 strain

Father helping son with face mask Father helping son with face mask

You may have heard about the COVID‑19 Mu variant after cases were reported across the U.S., including in North Texas. Variants are versions of a virus that have changed as the virus spreads. Mu is one version of the COVID‑19 virus that the World Health Organization (WHO) is monitoring as a "variant of interest."

What does the Mu variant mean for your family's health? Jeffrey Kahn, M.D., Director of Infectious Disease at Children's Health℠ and Professor at UT Southwestern, shares what health experts know about the Mu variant so far and how it may affect your family.

What is the Mu variant of COVID‑19?

The Mu variant, also known as B.1.621, was first detected in Colombia in January 2021. On August 30, 2021, WHO added Mu to its "variants of interest" list. That means the strain is spreading and needs more study to confirm if it's more contagious, causes more severe symptoms or shows resistance to vaccines as compared to the original SARS-CoV-2 virus.

Four other COVID‑19 strains (Alpha, Beta, Gamma and Delta) are considered "variants of concern" by WHO. A variant of concern means there is evidence that a variant is more contagious and/or can make people sicker. In the U.S., the Delta variant is the only variant of concern noted by the Centers for Disease Control and Prevention (CDC).

How widespread is the Mu variant?

As of September 2021, the Mu variant has spread to at least 40 countries and continues to be most prevalent in Colombia and Ecuador. However, the Mu variant, so far, only accounts for 0.1% of cases in the U.S.

According to the CDC, the Mu variant has declined in the U.S. since it peaked in late June. The highly contagious Delta variant currently is the strain behind 99% of cases in the U.S.

Is the Mu variant more contagious?

It's too early to tell if the Mu variant is more contagious than the Delta variant, the strain responsible for the current wave of infections in the U.S. Although health experts believe Mu has mutated from the more contagious Delta and Alpha variants, there's no evidence that Mu is more contagious. Health officials will continue to monitor it.

Do the COVID‑19 vaccines protect against the Mu variant?

Mu also has mutations associated with the Beta variant, which is currently more resistant to the COVID‑19 vaccines. However, health experts need more data before determining if Mu is more resistant to the immunity produced by vaccines. Current data shows that the COVID‑19 vaccines are highly effective at preventing serious COVID‑19 illness.

The longer we allow the virus to be transmitted in a population, the greater the likelihood of new variants emerging.
Dr. Jeffrey Kahn

How can you protect your family from COVID‑19 variants?

The best way to protect your family from COVID‑19 and its variants is for everyone who is eligible to get vaccinated. This is key to stopping the spread of COVID‑19, including the Mu variant, and to prevent new, potentially more dangerous variants from emerging.

"The longer we allow the virus to be transmitted in a population, the greater the likelihood of new variants emerging," Dr. Kahn says. "This is how viruses operate – they will continue to mutate as they spread. We have to take advantage of the opportunity we have now to reduce the spread of this virus, and that opportunity is vaccination."

In addition, your family can take daily precautions such as frequent hand washing, avoiding crowds and wearing face masks. The CDC recommends that children over the age of 2 and unvaccinated adults continue to wear masks indoors in public. Given the surge in cases due to the Delta variant, vaccinated people should also wear masks in areas with high spread of COVID‑19.

Learn more about COVID‑19

Children's Health is committed to remaining a trusted source of health information and care for you and your family during this time. See more resources to keep your family healthy at the Children's Health COVID‑19 hub.

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