The CDC's Nowcast data tracker, which displays COVID-19 estimates and projections for two-week periods, reflected that the KP.3.1.1 variant accounted for 57.2% of positive infections, followed by XEC at 10.7% in the two weeks starting on Sept. 29 and ending on Oct. 12.

The CDC is "monitoring the XEC variant," Rosa Norman, a CDC spokesperson told USA TODAY. This variant "is the proposed name of a recombinant, or hybrid, of the closely related Omicron lineages KS.1.1 and KP.3.3."

New COVID strain XEC is a recombinant strain of two variants in the Omicron family: KS.1.1 and KP.3.3. The hybrid strain was first reported in Berlin in late June but has spread across Europe, North America and Asia, with Germany, France, the Netherlands and Denmark leading the charge.

The XEC variant has reportedly been identified in 15 countries across the world, with experts warning the strain could be the 'next' to spread. While the UK Health Security Agency has yet to provide detailed data on the strain,