The "mu" coronavirus variant is now officially a "variant of interest"—and scientists naming COVID variants are now halfway through the Greek alphabet. The mu variant, also known as B.1.1621, was given the designation this week by the World Health Organization. The WHO warned that the variant has a "constellation of mutations that indicate potential properties of immune escape," meaning it could be a threat to people with immunity due to vaccination or earlier infection, the CBC reports. The WHO says the virus was first detected in Colombia in January and is most prevalent in that country, where it accounts for almost 40% of cases.
The WHO says mu has been detected in 39 countries worldwide, but it only accounts for 0.1% of COVID cases in globally. In the US, where the delta variant is believed to make up 99% of COVID cases, Dr. Anthony Fauci says the mu variant is not an "immediate threat," the New York Times reports. "Bottom line, we are paying attention to it,” he said Thursday. "We take everything like that seriously, but we don't consider it an immediate threat right now." (The WHO is also concerned about a new variant found in South Africa.)