"It doesn't have what it takes to beat Delta, not yet at least, but I am worried about what happens if nothing stronger can take out Delta."
Snack Pax Sept 19, 2021
SARS-CoV-2 CB.1.621 Mu Variant
The Mu Variant was first detected in Colombia, and had a real potential to cause some serious harm. It was not more infectious but it certainly had a great deal of lethality. The WHO still lists the variant as a Variant of Interest because there is ample evidence that it is still out there.