The U.S. Centers for Disease Control and Prevention (CDC) said on Wednesday the new BA.2.86 lineage of coronavirus may be more capable than older variants in causing infection in people who have previously had COVID-19 or who have received vaccines.
CDC said it was too soon to know whether this might cause more severe illness compared with previous variants.
But due to the high number of mutations detected in this lineage, there were concerns about its impact on immunity from vaccines and previous infections, the agency said.
Scientists are keeping an eye on the BA.2.86 lineage because it has 36 mutations that distinguish it from the currently-dominant XBB.1.5 variant.
CDC, however, said virus samples are not yet broadly available for more reliable laboratory testing of antibodies.
The agency had earlier this month said it was tracking the highly mutated BA.2.86 lineage, which has been detected in the United States, Denmark and Israel.
CDC said on Wednesday the current increase in hospitalizations in the United States is not likely driven by the BA.2.86 lineage.