The Omicron subvariant XBB is expected to account for 18.3% of the COVID-19 cases in the United States, up from 11.2% in the previous week, the U.S. Centers for Disease Control and Prevention (CDC) said on Friday.

The XBB variant has been driving up cases in parts of Asia, including Singapore, and some experts have said it is more transmissible but less severe.

The variant is expected to become the dominant one in parts of the U.S. Northeast in the week ended Dec. 24, according to the CDC.

Overall, the BQ.1.1 and BQ.1 remain the dominant circulating variants in the week ended Dec. 24, accounting for 63.1% of the cases, compared with 64.6% a week ago, the CDC said.