The mu coronavirus variant has been detected in 49 states and 42 countries, according to estimates, as health officials keep an eye on the strain to see if it becomes dominant.

The strain, also known as B.1.621, was first identified in Colombia in January and was added to the World Health Organization’s (WHO) "variants of interest" list, however 49 U.S. states and the District of Columbia have since detected the mu variant, with the exception of Nebraska, according to estimates compiled by Outbreak.info. States with a higher estimated prevalence of the variant include Alaska and Hawaii, though nationwide the variant has been detected in less than 1% of samples.

The news comes as the U.S. exceeded 40 million COVID-19 cases since the pandemic began, according to data from Johns Hopkins University. More than 4 million infections were reported in the last month, and the country has logged a total of at least 649,134 virus-related deaths.

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Dr. Anthony Fauci, the government’s leading infectious disease expert, on Sunday said the delta variant represented over 99% of the cases, adding that the mu varient demonstrated mutations that "indicate that it might evade the protection from certain antibodies."

He said the mu variant was "not an immediate threat."

California logged the highest number of samples containing the mu variant, with at least 384 cases, Newsweek reported, but the total translates to 0.2% of the state’s sequenced samples. As of Sept. 3, Los Angeles County health officials announced 167 mu variant cases sequenced between June and August, with the bulk of mu cases sequenced in July. 

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"The Mu variant is found to have key mutations linked to greater transmissibility and the potential to evade antibodies," a statement from LA County Public Health reads. "More studies are needed to determine whether Mu variant is more contagious, more deadly or more resistant to vaccine and treatments than other COVID-19 strains."

"The identification of variants like mu, and the spreading of variants across the globe, highlights the need for L.A. County residents to continue to take measures to protect themselves and others," Dr. Barbara Ferrer, director of LA County Public Health, added in the statement. "This is what makes getting vaccinated and layering protections so important. These are actions that break the chain of transmission and limits COVID-19 proliferation that allows for the virus to mutate into something that could be more dangerous."

Fox News' Edmund DeMarche contributed to this report.