The past two and a half years of the pandemic have been characterized by frustrating fits and starts. Just when it feels like the risk is subsiding, a new Covid-19 variant (or subvariant) arises. That appears to be what’s happening with a subvariant of the Omicron family: BA.5, which is spreading rapidly around the country; the subvariant now accounts for 65 percent of new Covid-19 infections in the United States.
