Growth Of ‘Most Transmissible Subvariant’ XBB.1.5 Worries Health Officials
The World Health Organization says the omicron strain XBB.1.5, which has become the dominant variant in the U.S. over a matter of weeks, could drive cases up. Dr. Ashish Jha, White House pandemic response coordinator, called its growth "stunning" but cautioned against panic. Scientists are working to determine if the subvariant also causes more severe illness.