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Should we be concerned about the COVID-19 Mu variant?

Monica Robins answers questions about the Mu variant, plus other variants of concern or interest.

CLEVELAND — So here's the question we keep getting: Do I need to be worried about the Mu variant?

COVID-19 began mutating since it first emerged. It’s already undergone hundreds if not thousands of changes.

That said, the Centers for Disease Control and the World Health Organization break down the mutations into three categories. Variants of Interest (VOI), Variants of Concern (VOC) and Variants of High Consequence.

Let me calm you down first: There are no Variants of High Consequence at this time. That would be a variant where nothing worked against it, not a vaccine or any type of medical treatment. That's the worst case scenario in a pandemic.

The WHO has nine variants of concern or interest.

The Variants of Concern in the U.S. are Alpha, Beta, Gamma and Delta.

But at this point, Delta is the predominant variant making up about 96% of new COVID-19 cases.

Currently, the WHO lists Mu as a Variant of Interest. It means it’s being watched closely because the genetic changes may make it easier to spread and cause more severe disease and has the potential to evade the protection of vaccines or even natural protection from previous variants. Meaning antibodies from a previous COVID infection couldn’t fight it either.

RELATED: World Health Organization tracking new COVID-19 variant 'Mu' with potential to evade immunity

Mu is the 12th letter of the Greek alphabet. Meaning the behaviors of 12 variants have made the list to watch. Three have already been taken off the list, Theta, Zeta and Epsilon are no longer on the VOI list. But there are at least a dozen more that haven’t been named yet.

Mu is a Variant of Interest in the U.S. It’s been discovered in 49 states, but so far it hasn’t made much of a dent in COVID cases. For perspective, Delta showed up in India in December 2020 and Mu showed up in Colombia in January of this year. But Delta managed to become the predominant variant nearly around the world in just eight months and Mu’s cases are still relatively very low.

So what makes a variant “interesting?”

The Eta variant showed up in the UK and Nigeria. It has the potential to reduce the effectiveness of some monoclonal antibody treatments, according to the CDC. So far, cases have not been identified in the U.S.

The Iota variant was first identified in New York. It is being watched for "reduced susceptibility to the combination of bamlanivimab and etesevimab monoclonal antibody treatment.” Although there are three monoclonal antibody treatments available in the U.S. so there are alternative treatments for this one.

The Kappa variant was discovered in India and while the vaccines work against it, the efficacy is somewhat lower. As is natural antibody protection.

The Lambda variant is not listed as a variant of interest by the CDC, but it is listed by WHO. Detected in 29 countries, it may spread more quickly than other milder versions of the virus. It’s primarily in South America and especially in Peru.

What are the Variants of Concern?

The CDC says Alpha spreads faster than other variants and may cause people to get sicker and die. This was originally known as the U.K. variant and was rampant in the U.S. during the second wave. The vaccines work against it.

Beta was originally identified in South Africa and also spreads fast but doesn’t seem to cause more severe illness or death. Vaccines work against it, but breakthroughs have been reported. The concern is that certain monoclonal antibody treatments are less effective.

The Gamma variant was first identified in Japan and Brazil. It spreads fast but doesn’t seem to cause more significant illness or death. Vaccines work against it although there have been breakthrough infections reported. Also, certain monoclonal antibody treatments are less effective against it.

The Delta variant is the most concerning variant currently. First identified in India it is now responsible for the overwhelming majority of cases in the U.S. It spreads faster than all other variants and is more likely to cause more severe illness according to the CDC.

Vaccines do work against it, but breakthrough infections have been reported. Preliminary evidence suggests that those fully vaccinated who become infected with Delta may transmit it to others. Certain monoclonal antibody treatments are also less effective against this variant.

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