In its COVID-19 Weekly Epidemiological Update, the WHO said the Mu variant, or B.1.621, was classified as a variant of interest on August 30, 2021.
The Mu variant was first identified in Columbia in January 2021. Since then, “there have been a few sporadic reports of cases of the Mu variant and some larger outbreaks have been reported from other countries in South America and in Europe,” the WHO said.
The WHO also expressed concern about the potential of the Mu variant to evade vaccines and treatments. “Preliminary data presented to the Virus Evolution Working Group show a reduction in neutralization capacity of convalescent and vaccine sera similar to that seen for the Beta variant, but this needs to be confirmed by further studies.”