After the busy holiday season of 2023, a new COVID-19 strain—called JN.1—has emerged. This variant was a blip on the radar in mid-November, but it quickly grew to become the most common COVID-19 variant in the U.S. Now, JN.1 is responsible for nearly 62 percent of COVID-19 cases in the United States.

Sure, there have been plenty of COVID-19 variants that have come and gone in the past. But cases of the virus have been steadily increasing across the country, and ER visits and hospital admissions linked to COVID-19 just shot up this week. Right now, it seems like everyone is getting sick.

So, what’s the deal with JN.1, and how concerned should you be about this new variant? Infectious disease doctors break it down.

What is the JN.1 variant?

JN.1 is a derivative of the Omicron variant, explains Thomas Russo, MD, a professor and chief of infectious diseases at the University at Buffalo in New York. “Its parent is BA.2.86—that’s the variant that got a lot of attention this summer that had a large number of spike protein mutations,” Russo says. (The spike protein is what SARS-CoV-2, the virus that causes COVID-19, uses to latch onto your cells and infect you.)

“JN.1 has an additional mutation on top of BA.2.86,” Russo says.

Are the JN.1 symptoms any different from previous variants?

The symptoms of COVID-19 have been pretty consistent for months, regardless of which variant causes it. Still, the Centers for Disease Control and Prevention (CDC) says these are the most common symptoms you might have with JN.1, or any variant of COVID-19:

- Fever or chills

- Cough

- Shortness of breath or difficulty breathing

- Fatigue

- Muscle or body aches

- Headache

- New loss of taste or smell

- Sore throat

- Congestion or runny nose

- Nausea or vomiting

- Diarrhea

Does the fall 2023 updated vaccine work against JN.1?

Yes, the latest COVID-19 vaccine works against JN.1. “There’s some data that suggest that we get a 10- to 13-fold increase in neutralizing antibodies against JN.1 with the updated formulation,” Russo says. “There’s good reason to believe that getting the updated formulation will be protective against JN.1.”

But Russo points out that the COVID-19 vaccine is “imperfect” against keeping you from getting infected. “The goal is really to minimize the development of severe disease and hospitalization,” he says.

What should I do if I test positive for JN.1?

It’s unlikely you’ll know which COVID-19 variant you have if you happen to test positive. However, if you get a positive test result right now, the odds are high that you have JN.1. The CDC's recommendations are the same as they’ve been for the past few months: You should stay home and isolate for five days after your positive test result, and wear a high-quality mask for 10 days when you’re around others.

If you’re considered high risk for serious complications from COVID-19, meaning you have diabetes or a chronic lung condition like asthma, Russo recommends contacting your doctor. You may qualify for an antiviral medication like Paxlovid or molnupiravir, which can lower the risk of serious complications from the virus.

What you shouldn’t do if you happen to get JN.1: Panic. “This virus, like many other respiratory viruses, is endemic and will continue to evolve—forever—in an effort to infect a highly immune population,” says Amesh A. Adalja, MD, an adjuct assistant professor at the Johns Hopkins Center for Health Security. “Cases will go up and down, variants will come and go, but most people have risk acclimatized to the virus and can navigate their lives knowing it’s ever-present and that there are more tools to cope with this virus than any other respiratory virus.”

Do COVID tests still work for the new JN.1 variant?

Yes, COVID-19 tests still work for the new variant. In fact, you can get free tests from the federal government right now. Russo recommends stocking up for the just in case.

“It’s not too late to get vaccinated, and it’s not too late to stock up on those home tests,” he says.