
The highly contagious Omicron subvariant XBB jumped to 18% of national prevalence and accounted for more than 50% of COVID-19 cases in the Northeast, coinciding with holiday travel for millions of Americans.
In the week ended Dec. 24, XBB was estimated to account for 18.3% of the COVID-19 cases in the United States, up from 11.2% in the previous week, according to the US Centers for Disease Control and Prevention on Friday (CDC).