The JN.1 variant already dominates in the US.

As far as experts know, JN.1 does not appear to cause severe illness in most people, although even a mild case can make you feel “pretty bad for three or four days,” Schaffner said. The symptoms of a JN.1 infection are similar to those caused by previous Covid variants, including cough, fever, body aches and fatigue.

To protect against severe infection and illness, experts continue to recommend wearing masks, improving ventilation indoors whenever possible, staying home if sick, and getting the latest Covid vaccine.

Preliminary research shows that the updated COVID-19 vaccines released in September produce effective antibodies against JN.1, which is related, albeit distantly, to the XBB.1.5 variant, for which the vaccines were designed. People may not accumulate as many antibodies against JN.1 as they do for XBB.1.5, but the levels should still reduce the risk.

“Among those who were recently infected or received a booster dose, cross-protection against JN.1 should be quite decent, our laboratory studies show,” said David Ho, a virologist at Columbia University who led the investigation on JN.1 and Covid vaccines, which was published as a preprint article in early December. Rapid testing also remains a valuable tool, and the CDC says tests already on the market work well at detecting the JN.1 variant.

There are signs that COVID-19 cases are on the rise once again. The week of Dec. 10, there were just under 26,000 coronavirus-related hospitalizations, a 10 percent increase from nearly 23,000 the previous week. But Covid hospitalization numbers are still much lower than during the height of the first Omicron wave in January 2022 and, so far, are only half of what they were during the peak of the ‘tripledemic’ last winter, when cases of COVID-19, influenza and RSV emerged at the same time.