The omicron subvariant BA.2 is continuing to gain ground in the U.S., according to Covid-19 tests sequenced over the last two weeks. Helix, a San Diego-based genomics firm, has been watching the BA.2 variant since it first popped up in the U.S. in early January. Although it was initially slow to take hold, Helix now estimates that 50% to 70% of all Covid cases nationwide are BA.2.
Data from the U.K. — where BA.2 has already caused cases to spike — show the country’s rise in infections began around the same time that BA.2 surpassed the 50% mark of overall cases. So far, the variant appears to be no more severe than the initial omicron strain, but there’s concern about its ability to reinfect people and its links to long Covid.