Here’s what we know about the mu variant

Cases of the WHO-designated ‘variant of interest’ have been reported in the United States, Colombia, South Korea and parts of Europe

A woman wearing a face mask to help curb the spread of the coronavirus walks across an intersection in Tokyo on Sept. 2. (Hiro Komae/AP)

A coronavirus variant known as “mu” or “B.1.621” was designated by the World Health Organization as a “variant of interest” earlier this week and will be monitored by the global health body as cases continue to emerge across parts of the world. It is the fifth variant of interest currently being monitored by the WHO.