For a third season, COVID-19 cases are rising ahead of the holidays, this time with a more recent variant driving infections.
Cases of JN. 1 infections rose from just more than 8% at the end of November to double digits by Dec. 9, according to CDC data.
International health experts say the sudden jump isn’t cause for concern—yet.
Here’s what you need to know:
What is JN.1?
The JN.1 variant is closely related to another omicron subvariant named BA.2.86, according to the CDC.
Health officials started tracking BA.2.86 in August but noticed some cases had a single change to the spike protein, the part of a virus that penetrates host cells to cause infection, according to the CDC.
JN.1 was first detected as its own variant in the United States in September, the CDC reported, and has since been identified in 11 countries.
The variant made up just 0.1% of cases at the end of October, according to CDC data, but that number has now increased exponentially.
“The continued growth of JN.1 suggests that it is either more transmissible or better at evading our immune systems,” the CDC said at the beginning of December.
This means the change to the spike protein may make it easier for the virus to get into cells than previous variants or make it harder for human immune systems to identify the virus as COVID-19.
International health experts also noted the trend, with JN.1 officially classified as its own variant by the World Health Organization on Dec. 19.
“Based on the available evidence, the additional global public health risk posed by JN.1 is currently evaluated as low,” the WHO said in a post on X, formerly known as Twitter. “Despite this, with the onset of winter in the Northern Hemisphere, JN.1 could increase the burden of respiratory infections in many countries.”
Does the updated COVID booster protect against JN.1?
The CDC says the JN.1 variant is closely related enough to previous variants that the updated COVID-19 booster shot will provide protection.
“The spike protein—called a ‘spike’ because it looks like tiny spikes on the virus’ surface—plays a crucial role in helping the virus infect people. Because of this, the spike protein is also the part of the virus that vaccines target, meaning vaccines should work against JN.1 and BA.2.86 similarly,” the CDC said.
The agency continued by saying it expects “treatments and testing to remain effective” against JN.1, in line with previous variants.
The most recent COVID-19 booster was approved by the Food and Drug Administration and then recommended by the CDC in September, but a large number of Americans have opted out of the shot.
Do I need the new COVID booster?
The vaccine is recommended for everyone over the age of six months, regardless of previous vaccine status, the CDC says.
Despite this, fewer and fewer Americans are adding the shot to their regular seasonal vaccines, like the flu shot.
By the middle of November, only 36 million adults and 3.5 million children had received the latest shot, equivalent to about 14% of the American public, ABC News reported.
That’s compared to the nearly 70% of Americans who completed the primary series of COVID-19 vaccines, McClatchy News reported.
Cases of JN.1 have seen some of the highest increases in Midwestern states, CDC data shows, correlating with a pocket of the U.S. that has been particularly hesitant to get the new shot.
Ahead of the holidays, the CDC reiterated the vaccine, masking and keeping your distance when you might be sick are still the most effective ways to prevent a COVID-19 infection and prevent its spread.
The agency said this also extends to other respiratory illnesses making the rounds this season.
“Many viruses spread more during the holiday season, so it is important to get all recommended vaccines, including flu, COVID-19 and RSV, as soon as possible,” the CDC said. “This will give you the best protection against these respiratory diseases, including while traveling and gathering with family and friends. These vaccines will also make your illness less severe if you do get sick.”

News
Johns Hopkins Researchers Uncover a New Way To Kill Cancer Cells
A new study reveals that blocking ribosomal RNA production rewires cancer cell behavior and could help treat genetically unstable tumors. Researchers at the Johns Hopkins Kimmel Cancer Center and the Department of Radiation Oncology and Molecular [...]
AI matches doctors in mapping lung tumors for radiation therapy
In radiation therapy, precision can save lives. Oncologists must carefully map the size and location of a tumor before delivering high-dose radiation to destroy cancer cells while sparing healthy tissue. But this process, called [...]
Scientists Finally “See” Key Protein That Controls Inflammation
Researchers used advanced microscopy to uncover important protein structures. For the first time, two important protein structures in the human body are being visualized, thanks in part to cutting-edge technology at the University of [...]
AI tool detects 9 types of dementia from a single brain scan
Mayo Clinic researchers have developed a new artificial intelligence (AI) tool that helps clinicians identify brain activity patterns linked to nine types of dementia, including Alzheimer's disease, using a single, widely available scan—a transformative [...]
Is plastic packaging putting more than just food on your plate?
New research reveals that common food packaging and utensils can shed microscopic plastics into our food, prompting urgent calls for stricter testing and updated regulations to protect public health. Beyond microplastics: The analysis intentionally [...]
Aging Spreads Through the Bloodstream
Summary: New research reveals that aging isn’t just a local cellular process—it can spread throughout the body via the bloodstream. A redox-sensitive protein called ReHMGB1, secreted by senescent cells, was found to trigger aging features [...]
AI and nanomedicine find rare biomarkers for prostrate cancer and atherosclerosis
Imagine a stadium packed with 75,000 fans, all wearing green and white jerseys—except one person in a solid green shirt. Finding that person would be tough. That's how hard it is for scientists to [...]
Are Pesticides Breeding the Next Pandemic? Experts Warn of Fungal Superbugs
Fungicides used in agriculture have been linked to an increase in resistance to antifungal drugs in both humans and animals. Fungal infections are on the rise, and two UC Davis infectious disease experts, Dr. George Thompson [...]
Scientists Crack the 500-Million-Year-Old Code That Controls Your Immune System
A collaborative team from Penn Medicine and Penn Engineering has uncovered the mathematical principles behind a 500-million-year-old protein network that determines whether foreign materials are recognized as friend or foe. How does your body [...]
Team discovers how tiny parts of cells stay organized, new insights for blocking cancer growth
A team of international researchers led by scientists at City of Hope provides the most thorough account yet of an elusive target for cancer treatment. Published in Science Advances, the study suggests a complex signaling [...]
Nanomaterials in Ophthalmology: A Review
Eye diseases are becoming more common. In 2020, over 250 million people had mild vision problems, and 295 million experienced moderate to severe ocular conditions. In response, researchers are turning to nanotechnology and nanomaterials—tools that are transforming [...]
Natural Plant Extract Removes up to 90% of Microplastics From Water
Researchers found that natural polymers derived from okra and fenugreek are highly effective at removing microplastics from water. The same sticky substances that make okra slimy and give fenugreek its gel-like texture could help [...]
Instant coffee may damage your eyes, genetic study finds
A new genetic study shows that just one extra cup of instant coffee a day could significantly increase your risk of developing dry AMD, shedding fresh light on how our daily beverage choices may [...]
Nanoneedle patch offers painless alternative to traditional cancer biopsies
A patch containing tens of millions of microscopic nanoneedles could soon replace traditional biopsies, scientists have found. The patch offers a painless and less invasive alternative for millions of patients worldwide who undergo biopsies [...]
Small antibodies provide broad protection against SARS coronaviruses
Scientists have discovered a unique class of small antibodies that are strongly protective against a wide range of SARS coronaviruses, including SARS-CoV-1 and numerous early and recent SARS-CoV-2 variants. The unique antibodies target an [...]
Controlling This One Molecule Could Halt Alzheimer’s in Its Tracks
New research identifies the immune molecule STING as a driver of brain damage in Alzheimer’s. A new approach to Alzheimer’s disease has led to an exciting discovery that could help stop the devastating cognitive decline [...]