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CLEVELAND (WJW/NEXSTAR) — Recently added to the World Health Organization’s list of coronavirus variants of interest, the B.1.621, or mu variant, has been detected in 49 states.

That’s according to a report from FOX News, which cites estimates compiled by

Nebraska is reportedly the only state where the mu — or B.1.621 — variant has not yet been detected.

The mu variant was first identified in Colombia in January 2021, but wasn’t officially labeled as a variant of interest (VOI) until Aug. 30, according to the Weekly Epidemiological Update published last week.

“The mu variant has a constellation of mutations that indicate potential properties of immune escape,” the organization wrote, noting that vaccinated individuals appear to show a “reduction in neutralization capacity” against mu.

As of last week, WHO indicated there were only “some” reports of larger outbreaks of mu, specifically in South America and Europe, along with “a few sporadic reports of cases.”

In New York City, Health Commissioner Dr. Dave Chokshi said the percentage of the Mu variant in the city has decreased. It is making up less than 1% of cases in the city as the delta variant continues to make up almost all the cases.

“We’re aware of this variant, we have been tracking it in New York City. The prevalence has actually decreased significantly and so, our public health guidance remains the same,” Chokshi said.

In total, WHO says the variant has been reported in 39 countries. 

WHO said further studies are needed to determine the characteristics of the mu variant. Other VOI being monitored by WHO include eta, iota, kappa and lambda.

The organization has also listed several variants of concern, or VOC, which include the alpha, beta, gamma and delta variants. These variants are similar in that they meet the criteria for a VOI, but are associated with either an increase in virulence, a decrease in effectiveness of public health measures, or a “detrimental change in COVID-19 epidemiology,” among other possible factors.