CDC tracks new COVID-19 variant XBB

The CDC is keeping an eye on a new COVID-19 variant known as XBB that represents more than 5% of COVID-19 cases in the Northeast and 3.1% of new cases across the US, based on the agency's preliminary estimates. The new subvariant may have emerged from the Omicron subvariants BA.2.10.1 and BA.2.75, and tracking of XBB has been prioritized "because it had quite a number of substitutions different from the currently circulating viruses in the [receptor-binding domain], which meant that it might be an escape variant," said Derek Smith, director of the Center for Pathogen Evolution at the University of Cambridge.