Norovirus is continuing to spread rapidly across the United States this month, forcing schools to close and state health officials to issue public health warnings.
The highly contagious virus, also known as “winter vomiting disease,” results in an average of 20 million cases and 900 deaths each year, according to the U.S. Centers for Disease Control and Prevention.
There have been more than 150 outbreaks of the infectious disease in 2025, agency data shows, with the virus spreading mainly through the central U.S.
The highest numbers of cases are in Montana, Wyoming, Alabama and Colorado, according to health information platform Epic Research.
But recent outbreaks in Massachusetts and Michigan have sent dozens of students and staff members home, and a wave of cases in Virginia have stressed emergency rooms, WJLA reports.
School disruptions
Roberts Elementary School in Medford, Massachusetts, closed for a second day Friday after there were more than 130 student absences Wednesday. More than 20 staff members said they were experiencing similar symptoms, the school said.
The closure comes nearly a month after Detroit’s Wilson Middle School closed due to a suspected outbreak, potentially tied to turkey meat that was served at lunch.
What was causing the outbreak in Medford was unclear and the school building has been “deemed safe and clean” by the state’s Board of Health.
“A professional company is currently performing a deep clean of the school today, which includes all classrooms, door knobs, kitchen equipment, and frequently touched surfaces,” the school wrote in a post on its website.
In Virginia, health experts have reported rising cases. Public schools in Fairfax County sent letters to parents reporting a spike in students experiencing vomiting and diarrhea at several schools, WJLA reported.
“It’s absolutely elevated,” Richmond City Health District’s Dr. Melissa Viray told WRIC. “But it’s not surprising to me that at this point in the year we are seeing increases in this sort of disease activity.”
Winter surge safety tips
Doctors had expected a surge during the winter months. Last winter, dozens of outbreaks were reported in the first week of December.
Anyone can become infected, though children under five years old, older adults and people with weakened immune systems are more likely to develop severe infections.
Typical symptoms include nausea, stomach pain, fever, head and body aches, and diarrhea and vomiting that can lead to dehydration and even death.
Most people who are infected get better within 24 to 72 hours, but they can still spread the virus for two weeks after they show symptoms. To prevent infection, experts ask people to wash their hands for at least 20 seconds and often. Hand sanitizer cannot kill norovirus.
“Alcohol can’t break the shield. A detergent like soap can most of the time,” Dr. Michelle Barron, UCHealth’s senior medical director of infection prevention and control, said in a statement.
People should also be sure to wash fruits and vegetables, clean and disinfect any contaminated surfaces, wash laundry in hot water to kill any bacteria and cook shellfish thoroughly.
Some outbreaks are tied to oysters and clams, which can harbor the virus. While the U.S. is not yet to the level of last year’s surge, it’s still too soon to predict how severe this season will be, Dr. Scott Roberts, an assistant professor at the Yale School of Medicine, warned TODAY.com.
"Time will tell how bad it will get. Now is the time to be vigilant,” he said. “I expect things to get worse before they get better.”
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