The New York Times reports:

The most transmissible variant yet of the coronavirus is threatening a fresh wave of infections in the United States, even among those who have recovered from the virus fairly recently.

The subvariant of Omicron known as BA.5 is now dominant, according to federal estimates released Tuesday, and together with BA.4, another subvariant, it is fueling an outbreak of cases and hospitalizations.

Though the popularity of home testing means reported cases are a significant undercount of the true infection rate, the share of tests that come back positive is shooting upward and is now higher than during most other waves of the pandemic. According to the C.D.C., the risk from Covid-19 is increasing in much of the country.

“I think there’s an underappreciation of what it’s going to do to the country, and it already is exerting its effect,” said Eric Topol, a professor of molecular medicine at Scripps Research, who has written about the subvariant.

BA.5 and BA.4, both subvariants of the Omicron variant that swept the world during the winter, are the most capable versions of the virus yet at evading immunity from previous infections and vaccines. Both variants have mutations in their spike proteins that are different enough from earlier versions of the virus that they are able to dodge some antibodies. [Continue reading…]