Omicron XBB.1.5: CDC tracker and map show where the latest COVID-19 variant is spreading

With holiday travel behind us and workers returning to offices this week, a rapidly spreading subvariant of COVID-19 has public health officials concerned about a possible winter wave. 

According to recent projections from the Centers for Disease Control and Prevention (CDC), XBB.1.5—an offshoot of the stubbornly persistent omicron variant—was projected to make up just over 40% of all COVID-19 cases in the United States as of the week ending December 31. Although the figure could change (data presented in the CDC’s Nowcast modeling tool is based on estimates of variant proportions), it marks a dramatic increase from the prior week, when XBB.1.5 made up about 21% of projected cases. 

The CDC’s estimates show that the new variant is easily outcompeting BQ.1 and BQ.11, two omicron offshoots that were spreading rapidly in late fall.

Omicron first emerged as the dominant variant of COVID-19 over a year ago, and while all these confusing alphanumeric subvariant names may sound similar, the distinction matters to scientists who study viruses and contagious diseases. It’s too early to tell if this latest offshoot will cause significantly different symptoms or a more severe form of COVID-19, but there is evidence that it has a better ability to evade immunity, CNN reports.