The World Health Organization has added the "mu" strain to its list of COVID-19 "variants of interest." The strain, also know as B.1.621, was first documented in Colombia in January 2021 but didn’t ...

The mu variant is the fifth variant strain to earn the title of "variant of interest" from the WHO. Among the other variants tracked by the WHO is the delta variant — a mutant strain proven to be more ...

Lambda: Lambda or C.37 was designated a WHO Variant of Interest in June. The CDC doesn't mention it. Mu: Mu or B.1.621 caused a flurry of fear when it was declared a WHO Variant of Interest in August, ...

The XFG variant of the severe acute respiratory syndrome coronavirus 2 as continued to spread as the U.S. heads into peak Summer travel season. (Photo by I RYU/VCG via Getty Images) There’s another ...