New COVID strain quickly becomes most dominant in U.S.

The fast-spreading COVID-19 variant known as JN.1 is now the most prevalent in the U.S., accounting for more than 44% of cases as the virus expands domestically and internationally.

The big picture: JN.1's surge suggests it's either more transmissible or better at evading our immune systems than other strains in circulation, per the Centers for Disease Control and Prevention. But it's too early to tell how much it will drive an increase in infections or hospitalizations this winter.

Driving the news: JN.1 estimates shot up from 21.3% to 44.2% over the two weeks ending Dec. 23, according to the CDC, which noted the variant is showing up in more travelers and wastewater surveillance.

It was by far most prevalent in the Northeast, accounting for 56.9% of the cases in the Department of Health and Human Services' Region 2, which comprises New York, New Jersey and U.S. territories in the Caribbean.