Omicron BA.2 sub-variant now nearly a quarter of new COVID cases in U.S., CDC estimates

The BA.2 sub-lineage of the Omicron variant now makes up nearly a quarter of new COVID-19 infections nationwide, the Centers for Disease Control and Prevention estimated Tuesday, up from around 1 in 10 new cases just a week prior. 

Since January, Omicron has made up virtually all new infections in the U.S. Like in many countries abroad, most cases in the U.S. had been caused by a sub-lineage of Omicron known as BA.1. But while both BA.1 and BA.2 can be traced back to some of the earliest samples gathered of Omicron, BA.2 has only recently begun to climb in prevalence. 

BA.2's prevalence is the highest in the Northeast, according to the CDC's "Nowcast" estimates published Tuesday. In the region spanning New York and New Jersey, the agency estimates 39.0% of circulating viruses are BA.2. In New England, prevalence of BA.2 is at 38.6%.