Note: Information in this article was accurate at the time of original publication. Because information about COVID-19 changes rapidly, we encourage you to visit the websites of the Centers for Disease Control & Prevention (CDC), World Health Organization (WHO), and your state and local government for the latest information.
As cold winter weather drives people indoors and flu, colds, and other seasonal respiratory viruses circulate, SARS-CoV-2, the coronavirus that causes COVID-19, has continued to mutate and spread. The latest strain to attract attention is called JN.1, and so far, it appears to be highly transmissible.
It can be difficult, if not impossible, to predict the evolution of the coronavirus and its descendants. But the Centers for Disease Control and Prevention (CDC) projects that JN.1 cases will increase through the winter. The World Health Organization (WHO) also declared JN.1 a “variant of interest.”
“We don’t know much about this new subvariant just yet,” says Heidi Zapata, MD, PhD, a Yale Medicine infectious diseases specialist.
There are other subvariants, too, including HV.1, which in early December was the dominant strain in the United States, causing over 29% of cases, more than any other subvariant. (EG.5, which had been the dominant strain since the summer, dropped to second place in November and, by mid-December, accounted for less than 10% of cases. HV.1 is an EG.5 descendant and is considered to be similar to it.)
So far there is no evidence that JN.1 causes more severe cases of COVID or poses any more of a risk to public health than other circulating variants, the CDC says.
At the same time, COVID cases are rising, notes Dr. Zapata. “I would say the most important thing for people to know is that the virus is out there, as are respiratory syncytial virus [RSV] and the flu,” she says. “Any new subvariant is a sign that the SARS-CoV-2 virus is still evolving; it’s still here with us, and we can’t ignore it.”
Here, Yale Medicine answers three questions about JN.1.
