The highly transmissible XBB.1.5 omicron subvariant rose to the top of all COVID-19 strains circulating in the U.S. this week, according to data from the Centers for Disease Control and Prevention.
XBB.1.5 was responsible for 43% of new coronavirus cases this week, according to CDC estimates. It’s more than any other omicron subvariant that the agency tracks, and the rate is up from 30% of infections last week. It’s the only omicron subvariant that is increasing in prevalence, setting it up to dominate the variant scene in the coming weeks. The subvariant is already responsible for the vast majority of new cases in the Northeast.
The World Health Organization this week warned that XBB.1.5 could fuel a worldwide escalation in COVID-19 infections.
“Based on its genetic characteristics and early growth rate estimates, XBB.1.5 may contribute to increases in case incidence globally,” the organization said in its assessment of the strain. But it noted that growth advantage estimates are only from the U.S., so it rated its confidence in the assessment as “low.”
But COVID-19 cases in the U.S. are declining slightly, though experts believe the numbers to be widely underestimated as many rely on at-home COVID-19 tests that don’t get reported to health departments.
Coronavirus-related deaths, however, jumped this week to a level not seen since August. The CDC reported over 3,900 COVID-19 deaths in the U.S. this week.
COVID-19 transmission is considered “high” across most of the U.S., according to CDC data. But under the agency’s “community level” guidance, which diverges from transmission levels, Americans in just under 14% of counties should be masking while indoors.
WHO, on the other hand, amended its masking guidance this week to recommend that everyone wear masks in crowded spaces “irrespective of the local epidemiological situation, given the current spread of the COVID-19 globally.”