A new coronavirus variant that’s showing the potential to evade immunity is now being closely monitored by the World Health Organization and officials in the United States.
The Mu variant — named after the Greek letter, following convention — was first documented in Colombia and has “a constellation of mutations that indicate potential properties of immune escape,” according to a World Health Organization report published earlier this week.
The mutant was added to the WHO list of “variants of interest” on Monday. Variants of interest are those with genetic changes that could impact characteristics such as transmissibility or disease severity and cause significant community spread.
A variant of interest isn’t quite as bad as a “variant of concern” — such as the delta variant — which is defined as a mutant that causes increased spread and severity, or decreased effectiveness of public health measures such as vaccines or social distancing.
There have been a few “sporadic” reports of mu variant cases and outbreaks in South America and Europe, according to the WHO report.
Overall, Mu variant cases make up 0.1% of all infections globally, but prevalence in Colombia is about 39% and has consistently increased.
Related story: LA County confirms cases of potentially infectious Mu variant of COVID-19
When asked about the Mu variant during a Thursday press briefing, the nation’s top infectious disease specialist, Dr. Anthony Fauci, said, “We always pay attention to, at all times, variants. This variant has a constellation of mutations that suggests that it would evade certain antibodies … but there isn’t a lot of clinical data to suggest that, it is mostly laboratory in vitro data.”
Fauci said the Mu variant is being taken seriously and monitored closely, but isn’t a threat right now.
The Mu variant makes up 0.2% of coronavirus cases in the United States, according to the Centers for Disease Control and Prevention. The highly contagious delta variant still accounts for nearly all coronavirus cases in the U.S. right now.
Dr. Daniel Kuritzkes, chief of infectious disease at Brigham and Women’s Hospital, said it’s a bit too early to know if the Mu variant will be cause for concern, but it’s important to keep tabs the mutant’s progress.
“It seems given the fact that the variant has been detected in South America and England, and it’s been associated with some clusters and has these concerning mutations — there’s certainly good reason to be monitoring it closely,” Kuritzkes said.
There have been 44 cases of the Mu variant detected in England as of last week, according to Public Health England.
The United States has cycled quickly through several predominant variants since the pandemic began, said Kuritzkes. He noted that the Alpha variant, which originated in the United Kingdom and was once dominant in the U.S., was quickly replaced with the Delta variant.
There are several other variants of interest on the WHO list, including the Iota variant, which was first found in the U.S., the Kappa variant with origins in India, the Lambda variant found in Peru and the Eta variant detected in multiple countries.
