Health officials warn that the new COVID variant XEC, rapidly spreading in Europe, could become the predominant strain in the U.S. this winter.

The latest, highly contagious subvariants are driving infections, but new vaccines may help stem the tide of another wave — if people get immunized.

Another COVID-19 variant is on the rise this fall, hot on the heels of a massive summer surge of the virus. The variant, called XEC, is appearing worldwide. The SARS-CoV-2 virus mutation has also been spotted in at least half of the United States,