CDC wastewater also shows the XFG variant — nicknamed stratus — is most common in the U.S. Stratus can cause a “razor blade” sore throat and is considered a “variant under monitoring” by the World Health Organization. The WHO said the variant is only marginally better at evading people's immune systems and vaccines still work against it.

A new COVID variant is on the rise amid a nationwide summer surge of cases and it's on track to become the third most common strain. What to know in Tennessee.