Norovirus, commonly called “winter vomiting disease,” is rising across the United States, with levels increasing since mid-October, according to WastewaterSCAN, a national monitoring program run by Stanford and Emory. Wastewater data and CDC testing show the virus spreading earlier and faster than usual in some places, notably Louisiana, Michigan, and Indiana, although outbreak numbers remain lower than last year (there were 235 outbreaks during the same period in 2024).
Why now
Norovirus typically climbs during colder months. People spend more time indoors in close contact at schools, workplaces, public transit and holiday gatherings, which helps the virus move from person to person. Seasonal factors — lower vitamin D, drier air that weakens immune defenses, and conditions that let the virus survive better in cool, dry environments — also contribute.
Where it spreads
While cruise ships are often associated with norovirus, it spreads easily in many settings, including schools, nursing homes, restaurants and other crowded places where food, surfaces or hands can become contaminated.
How it spreads and symptoms
Norovirus is highly contagious and can spread through contaminated food, water, hands, or surfaces. Infection often begins quickly: symptoms typically start 12–48 hours after exposure and usually last 1 to 3 days. Common signs include sudden vomiting, diarrhea, abdominal pain and nausea; people may also experience headache, fatigue, low-grade fever or body aches. Only a tiny amount of virus is needed to cause infection, and it can survive on surfaces for days.
Prevention
– Wash hands thoroughly with soap and water. Alcohol-based hand sanitizers are less effective against norovirus.
– Disinfect high-touch surfaces with a bleach-based cleaner, especially after someone has been sick.
– Avoid sharing food, drinks or utensils in group settings.
– When someone in the household is ill, wash contaminated clothing and bedding on a hot cycle and handle items carefully to limit spread.
– If traveling or attending gatherings, be cautious around shared foods and crowded indoor spaces.
If you get sick
There’s no specific antiviral treatment for norovirus. Focus on staying hydrated and resting. Sip small amounts of fluid (for example, 1–2 tablespoons at a time) to replace losses from vomiting and diarrhea and to reduce the chance of triggering more vomiting. Oral rehydration solutions or electrolyte drinks can help. Rest and limit physical activity for the first 24–48 hours while symptoms are worst, then resume normal activities as you recover. Seek medical care if you experience signs of severe dehydration, persistent vomiting, weakness, or if you have a serious underlying medical condition.
Bottom line
Norovirus is spreading earlier this season in parts of the U.S., but simple hygiene and cleaning measures — especially soap-and-water handwashing and disinfecting surfaces — can greatly reduce your risk. Stay home if you’re sick, keep hydrated, and seek medical attention for severe or worsening symptoms.
