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.

COVID-19 cases are rising again in the United States, and the "stratus" variant might be to blame. The big picture: A summer outbreak of COVID-19 cases isn't a shocker. But it's arriving before children head back to school,