Why is that?

The U.S. has growing regional vaccine disparities, so there’s a high risk of Covid flare-ups when the weather turns colder. Fewer than 40 percent of Americans in many Southern states have received at least one shot, compared with 65 to 70 percent of New Englanders. By autumn, kids will return to in-person schooling, many families will hold large indoor gatherings, and immunity developed from previous infections may not provide full protection against variants. There are reports from India and Brazil of people who already had Covid once getting sick again with variants, and the U.K. is having an uptick in cases caused by the Indian strain.