GENEVA, Switzerland — The World Health Organization added another COVID-19 variant of interest to its list of “variants of interest.” Monday, the WHO said it is now monitoring the development of the “Mu” variant.
The Mu variant, officially known as B.1.621, was first detected in January in the South American nation of Colombia. The Mu variant is one of five variants listed by the WHO as “variants of interest.” Other strains on the list include Eta, Iota, Kappa, and Lambda. A few of those strains, including Lambda, have already been reported in the United States.
The WHO said variants of interest are strains of SARS-CoV-2 (COVID-19) that have “genetic changes that are predicted or known to affect virus characteristics such as transmissibility, disease severity, immune escape, diagnostic or therapeutic escape,” and have been “identified to cause significant community transmission or multiple COVID-19 clusters, in multiple countries with increasing relative prevalence alongside increasing number of cases over time, or other apparent epidemiological impacts to suggest an emerging risk to global public health.”
The WHO’s list of variants of interest is the second-highest level measuring variants, behind only “variants of concern.” Variants in the highest level include Alpha, the initial variant, and the Delta variant, currently uncontrollably spreading in Florida and many other U.S. states. The Delta variant was identified as a variant of interest on April 4 and moved to a variant of concern by May 11. Still, not every variant moves from variants of interest to variants of concern.
The Mu variant is the only variant of interest on the list that had a first case reported in 2021. The UK Guardian reported the Mu variant has already been seen in the United States and accounts for nearly 40 percent of COVID cases in Colombia. According to the Guardian, scientists in Britain said concern over Mu “comes from the particular mutations it carries” that “may help the virus evade immunity defences, which could give the variant an advantage over Delta as immunity rises into the autumn.”
According to the WHO, it will work on “a comparative assessment of variant characteristics and public health risks” of Mu and if necessary, “coordinated laboratory investigations with Member States and partners.”