A new Covid variant called XFG, or “Stratus,” has been spreading in the U.S. since March and is now driving higher infection levels. The CDC reports that as of the week of September 7, “the overall Covid activity level was classified as high, up from moderate just one week earlier.”

Scientists say XFG is more contagious than earlier strains because of spike protein mutations that let it partially evade antibodies from past infections or vaccines. This helps explain why it has become dominant so quickly.

Health experts stress that “current evidence does not indicate the XFG variant is more deadly,” but its fast spread raises risks for older adults, people with health issues, and the unvaccinated. Increased cases could strain hospitals and clinics in the coming weeks.

Preventive steps like updated vaccines, better ventilation, and “mask-wearing in crowded settings when local transmission rates are high” are still effective, according to officials.

The rise of XFG highlights how the virus continues to evolve. While not more severe, its stronger transmissibility shows that “the pandemic’s impact is far from over.”