Norovirus cases driven by ultra-contagious variant are surging. And hand sanitizer won't kill it
Norovirus, the infamous “winter vomiting disease,” is surging again across the United States.
Norovirus is a highly contagious stomach bug that causes sudden, often violent bouts of diarrhea and vomiting. If you’ve ever had norovirus, you know how miserable it is — one moment, you’re fine, the next, you’re stuck in gastrointestinal purgatory.
Unfortunately, outbreaks of norovirus are on the rise. According to WastewaterSCAN, which monitors diseases through municipal wastewater systems, norovirus levels are “high” nationally.
Norovirus concentrations are up 45% since November, and there’s been a significant upward trend in the last 3 weeks, Marlene Wolfe, Ph.D., professor at Emory University and program director at WastewaterSCAN, tells TODAY.com. Levels are currently the highest in the Midwest and Northeast.
Two schools in Massachusetts closed for several days this month due to suspected norovirus outbreaks after dozens of students were absent with stomach bug symptoms, NBC Boston reported.
Norovirus outbreaks are also surging on cruise ships.
The uptick in norovirus started slightly earlier than usual and appears to be driven by a newer variant of the virus, which fueled a harsh 2024-2025 season. Last winter, norovirus outbreaks surged to decade-high levels.
Norovirus is the leading cause of gastroenteritis, an inflammation of the stomach and intestines, Dr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center, tells TODAY.com. It’s also the most common cause of food poisoning.
Every year in the U.S., norovirus causes an average of 19–21 million illnesses, 109,000 hospitalizations and 900 deaths, per the U.S. Centers for Disease Control and Prevention.
Along with flu, norovirus is expected to keep spiking in the coming weeks. Here’s what to expect this winter, which norovirus symptoms to look out for, and how to protect yourself.
Norovirus surge
“We’re seeing upticks in norovirus across the system, but that’s not out of the ordinary. … It’s historically a winter bug,” Dr. Scott Roberts, assistant professor of infectious diseases at the Yale School of Medicine, tells TODAY.com.
Norovirus spreads year-round, but most outbreaks occur between November and April, per the CDC. “Everybody is huddled indoors and in close quarters, so it lends itself to spreading like wildfire once it does set up shop,” says Roberts.
The virus is notoriously difficult to control and can sweep through homes, schools, day cares and nursing homes.
There are about 2,500 norovirus outbreaks every year in the U.S., per the CDC.
Currently, outbreaks are rising. Between Aug. 1 and Dec. 11, there were 268 norovirus outbreaks reported by the 14 states participating in the CDC’s NoroSTAT program.
The percentage of norovirus tests coming back positive is also increasing. According to data from labs reporting to the CDC, the positivity rate was 12% for the week ending Dec.13. During the same week last year, the rate was 19%.
The CDC does not currently monitor norovirus through wastewater surveillance, which provides a more reliable early warning sign that cases are rising because most sick people don’t seek care or get tested for norovirus, says Wolfe.
However, WastewaterScan data show a clear early surge. “The concentration really started increasing around October,” says Wolfe.
Although cases are rising, the number of outbreaks at this point in the season is lower than it was last year and within the average range for this time of year, per the CDC.
“So far, we’re not yet to the level that we were at last year, which was really our worst year since pre-COVID … but it’s certainly going up,” says Roberts.
It’s too soon to predict how severe this season will be or when it will peak.
“Time will tell how bad it will get. Now is the time to be vigilant. I expect things to get worse before they get better,” Roberts says.
Norovirus GII.17 variant
Since the early 2000s, the majority of norovirus outbreaks have been caused by one strain, GII.4, NBC News reported previously.
About 10 years ago, a variant called GII.17 emerged in Asia and has taken off in recent years. During the 2024-2025 season, GII.17 caused 75% of norovirus outbreaks in the U.S., compared to less than 10% in 2023, according to a study from the CDC.
“Whenever there is a new strain, it’s really easy for it to start spreading rapidly, and that’s what we saw last year,” says Roberts.
It’s unclear whether GII.17 is more transmissible than GII.4, the experts note, but it’s possible that more people are susceptible to infection because they don’t have immunity.
Infection with norovirus is thought to provide some immune protection, but it’s not complete or long-lasting, says Schaffner.
“We don’t have a good sense of how long this immunity can actually protect us … but that immunity probably won’t protect you against another strain,” Roberts adds.
A susceptible population could give norovirus more opportunities to spread, but it’s unclear how this season will pan out.
Norovirus symptoms
“It’s really not subtle infection,” says Roberts. Norovirus often begins suddenly, within 12–48 hours after being exposed.
The most common symptoms of norovirus include:
- Vomiting
- Diarrhea
- Nausea
- Abdominal pain and cramps
Less common symptoms include a low-grade fever, chills and a headache, according to the CDC.
“Fortunately, it’s relatively brief. You’re miserable for about 48 hours, then you get better,” says Schaffner. Norovirus usually goes away on its own after one to three days.
However, norovirus can lead to fluid loss and dehydration, the experts warn. Some people are at higher risk for severe disease, complications and hospitalization, says Schaffner. These include children under the age of 5 and adults over 85.
Seek medical care if your symptoms persist after a few days, there’s blood in your stool or vomit, or you have signs of dehydration such as dark urine or dizziness, per the Cleveland Clinic.
Norovirus treatment
There is no specific treatment for norovirus, but symptoms can be managed with supportive care like rest and replenishing fluids, says Roberts. Sports drinks can help restore electrolyte levels.
“Don’t try to drink a lot all at once because it can come right back up,” says Schaffner.
In severe cases, a person may need intravenous fluids to prevent dehydration. “If you have concerns, contact your health care provider,” says Schaffner.
There’s no vaccine for norovirus, but a Moderna candidate is in phase 3 clinical trials.
How does norovirus spread?
“It’s a devilish virus because it can spread in so many ways, and it is so highly contagious,” says Schaffner.
An infected person can shed billions of virus particles in their stool and vomit. “It takes very few particles, between one and 10, to initiate an infection,” Schaffner adds.
Norovirus typically transmits though the oral-fecal route, says Roberts, when virus particles from feces end up in the mouth, often via dirty hands. “It’s easier to do than you think,” he adds.
Norovirus can be transmitted through:
- Direct contact with a sick person
- Touching contaminated objects then touching your mouth
- Consuming contaminated food or drinks
- Inhaling or swallowing aerosolized particles from vomit
A person infected with norovirus is most contagious from symptom onset until at least a few days after they feel better, the experts note. However, you can still shed the virus in your stool for two weeks after recovering, says Roberts.
Foods commonly involved in norovirus outbreaks include leafy greens, fresh fruits and undercooked shellfish, per the CDC.
How long does norovirus last on surfaces?
Norovirus particles can survive on surfaces, objects and even foods for up to two weeks, according to the Cleveland Clinic.
Cleaning and disinfecting contaminated surfaces is an important part of norovirus prevention.
What kills norovirus on surfaces?
The most effective household cleaner to kill norovirus is bleach, such as bleach wipes or bleach-based disinfectants, experts previously told TODAY.com. Norovirus isn’t susceptible to alcohol-based cleaning products.
Does hand sanitizer kill norovirus?
Norovirus is very hard to kill. Alcohol-based sanitizers and cleaners are not effective against norovirus because the virus particles have a firm outer shell that alcohol won’t break down, the experts note.
Instead, the virus needs to be physically washed off the hands. “You have to use soap and water, which literally picks up the virus and washes it down the drain,” says Schaffner.
Bleach-based cleaners are effective at killing norovirus on surfaces and objects.
How to prevent norovirus
It isn’t always possible to avoid norovirus — sometimes, it’s just bad luck. However, you can take steps to lower your risk of getting norovirus and spreading the infection to others.
- Wash your hands frequently, especially after using the bathroom and before eating.
- Disinfect contaminated surfaces and objects with bleach.
- Avoid direct contact with infected people.
- If infected, isolate for at least 48 hours.
- Avoid cooking for others when sick.
- Cook shellfish to at least 145 degrees Fahrenheit.
If you have questions or concerns, talk to your doctor.
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