JN.1, New, Highly-Mutated COVID Variant Could Cause Largest U.S. Waves

By | December 29, 2023

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.

Already, JN.1 dominates U.S. COVID infections, according to estimates by the U.S. Centers for Disease Control and Prevention released Friday. In two weeks it surpassed the previously dominant variant, HV.1, and is now double its size, comprising 44% of the country’s COVID infections—leaving all past leading variants sitting in the single digits, far behind, in the dust.

Hospitals currently aren’t under the same strain they have been during pandemic winters. Flu and RSV peaked early last year, putting undue pressure on the system early on. 

Whether this will remain the case will largely depend on the activity of “Pirola” JN.1, which could stress hospitals in some areas of the country if its wave lines up with flu and RSV waves, according to leading COVID forecaster Jay Weiland, oft cited by public health experts like Scripps Institute founder and director Dr. Eric Topol.

Already, some European countries like Germany, the Netherlands, and Denmark are seeing all-time high levels of COVID in wastewater, higher even than the Omicron spikes of early 2022, according to Weiland’s estimates.

COVID hospitalizations are rising in some countries like Singapore, which doesn’t see a true winter and, thus, doesn’t experience the typical seasonal spikes in respiratory diseases driven by increased indoor activity, weather, and similar factors.