JN.1—a new, highly mutated COVID variant—could cause one of the largest U.S. waves yet, experts say. When each state could see the variant peak

"Pirola" JN.1, a highly mutated COVID strain, is the wildcard in this season's winter respiratory disease forecast, experts say. (Credit: Getty Images)

Respiratory pathogens are on the rise this winter in the U.S., with signs so far pointing toward a significant, but not outlandish, season—perhaps a bit of a respite after last winter’s “tripledemic.” 

The wildcard in the forecast, however, could change the scene entirely. “Pirola” JN.1, the highly mutated Omicron strain, could send COVID infections skyrocketing to the second loftiest level the U.S. has seen so far. Coupled with other winter illnesses like RSV and flu, hospital capacity could again be tested this season, experts tell Fortune. It depends on a number of factors, including how intensely the new variant spreads in the U.S., vaccination rates, and how well waning COVID population immunity holds up.