What to Know About the COVID-19 JN.1 Variant

As cases of respiratory illness continue to spread this winter, the COVID-19 subvariant JN.1 has emerged as the most widely circulating variant in the United States and across the world, according to the Centers for Disease Control and Prevention.

JN.1, which is a subvariant of the Omicron variant, was first detected in the United States in September 2023.

“We are definitely seeing an uptick in COVID-19 cases and hospitalizations fueled by JN.1, which is more contagious,” says Dr. Magdalena Sobieszczyk, chief of the Division of Infectious Diseases at NewYork-Presbyterian/Columbia University Irving Medical Center.  “We’re seeing the aftermath of things like holiday gatherings, travel, fewer people taking precautions, and low uptake of the updated vaccine. But the silver lining is that we’re not seeing as many severe cases as we did in the past.”

Symptoms of JN.1 are like those of other variants: sore throat, congestion, nausea, and fatigue are commonly reported, Dr. Sobieszczyk says.

Dr. Sobieszczyk shares more with Health Matters on what you need to know about JN.1.

What are some contributors to the latest COVID-19 surge?
Dr. Sobieszczyk: Every winter we see an increase in respiratory infections: flu, RSV, and more recently, COVID-19. People have been staying indoors and congregating in settings with less ventilation, which gives the virus an opportunity to spread.

We’re seeing more COVID cases due to JN.1. At the end of October 2023, it made up less than 0.1% of circulating SARS-CoV-2 variants – the virus which causes COVID-19. By January 19, 2024, it accounted for up to approximately 88 percent of currently circulating variants, according to the CDC.

What are the symptoms of the COVID-19 variant JN.1?
JN.1 does not seem to cause more severe symptoms compared to other variants.

Common symptoms reported include sore throat, nausea, and diarrhea within a few days of the illness’ onset. Loss of smell may be less frequently reported.

There are a wide range of symptoms including fever, chills, fatigue, cough, muscle or body aches, and congestion.

What differentiates JN.1 from other subvariants?
JN.1 is an offspring of the earlier Omicron variants and closely related to BA.2.86. It seems to be more contagious and transmissible.

Every virus mutates. That’s what allows them to survive. They mutate by making mistakes in the processes of replication, which is how these variants emerge. Some mutations are good for the virus, helping it thrive and become easier to transmit, changing the way the virus behaves.

When we talk about variants of concern, these are viruses that have mutations that make them more contagious or may cause more severe COVID illness, or more resistant to vaccines and antiviral medications. But compared to the first Omicron surge, JN.1’s severity is not as robust. The overall number of virus-related illnesses that require emergency room visits is lower compared to last year, and COVID hospitalizations and percent of total deaths are down as well.

This shift is most likely related to the fact that we have more immunity in the general population, both from vaccines and prior infection. This protection can fade over time, but tends to last longer for preventing severe disease.

Other variants we are watching include HV.1. and JD.1.1, according to the CDC.

What are treatments for the subvariant?
For people with mild to moderate infection who are not hospitalized and are at risk of severe disease or hospitalization, treatment with antivirals is recommended, similar to other variants.

The first line of treatment is Paxlovid, an antiviral pill that reduces the amount of the virus that causes COVID-19 in the body and prevents symptoms from getting worse.

Though the viruses are mutating, there is still data to suggest that the medication is effective. There is a lot of research happening in this space, including looking for new antiviral treatments.

A question I often get asked is, “Why should I take Paxlovid, especially if I only have a mild case of COVID?” I do want to emphasize that it is still an area of important research with mixed data, but recent data suggests that there may be a benefit to reducing the risk of developing long-COVID, or post-COVID conditions, especially in individuals over age 50 and those with preexisting medical conditions.

It is important to keep in mind that some patients continue to have an increased risk of progressing to more severe COVID. Paxlovid is beneficial and recommended for people over the age of 50, or for those with underlying medical conditions such as high blood pressure or diabetes who are at risk of complications from COVID-19 and hospitalization.

Does the current vaccine protect against JN.1?
We are seeing good data that this updated vaccine can elicit robust antibodies against current and emerging SARS-CoV-2 variants. That’s good news for effectiveness of the vaccine in preventing some degree of infection and severe disease.

A report released in February 2024 from the CDC shared that the updated vaccine provided approximately 54 percent protection against symptomatic infection, compared with no receipt of the updated vaccine.

We are also seeing data that show that immunologic imprinting is less severe for this updated vaccine compared to the previous bivalent vaccine, which means the immune system has more of a robust and purposeful response to the current variants. This bodes well for its ability to respond to a newer variant that may be coming around the corner.

How can people best protect themselves against COVID-19?
I advocate for masking in congested or crowded settings, not just to protect against COVID-19 but other respiratory viruses.

In addition to COVID, flu season typically peaks between December and February, and we see cases into the spring.

I suggest people get their flu and COVID-19 vaccine, and if needed, the RSV vaccine. Currently, only 21 percent of adults in the United States have received the updated COVID vaccine.

Test when you feel sick, and remember to always wash your hands.

Magdalena Sobieszczyk, M.D., is the chief of the Division of Infectious Diseases at NewYork-Presbyterian/Columbia University Irving Medical Center and is the Harold Neu professor of infectious diseases in medicine at Columbia University Vagelos College of Physicians and Surgeons. Dr. Sobieszczyk is also a clinical virologist and the principal investigator of the Columbia Collaborative Clinical Trials Unit, funded by the National Institutes of Health, which has been advancing the science of infections like SARS-CoV-2 and HIV.