Norovirus is extraordinarily contagious, requiring as few as 18 viral particles to cause infection. For context, a single gram of an infected person’s stool can contain up to 5 billion infectious doses. That extreme mismatch between how little it takes to get sick and how much virus a sick person sheds is what makes prevention so challenging, and so important to get right.
Why Soap and Water Beats Hand Sanitizer
Alcohol-based hand sanitizers are nearly useless against norovirus. In lab testing, ethanol-based sanitizers reduced viral counts on contaminated hands by only 0.14 to 0.34 log, a negligible amount. Soap and water performed far better, achieving roughly a full log reduction, meaning it removed about 90% of viral particles compared to the sanitizer’s roughly 30–50%.
The reason comes down to the virus’s structure. Norovirus lacks a fatty outer envelope, which is the part that alcohol is good at dissolving. Without that vulnerable layer, ethanol simply doesn’t break the virus apart. Physical removal turns out to be what matters most: the friction of rubbing your hands together under running water mechanically dislodges viral particles and washes them down the drain. Researchers found that even a plain water rinse outperformed alcohol sanitizer, and that adding a rubbing motion improved results further.
Wash your hands for at least 20 seconds with soap and water, especially after using the bathroom, changing diapers, and before eating or preparing food. Keep hand sanitizer as a backup for situations where soap isn’t available, but don’t rely on it as your primary defense during norovirus season or an active outbreak.
Cleaning Surfaces the Right Way
Norovirus can survive on dry surfaces at room temperature for 21 to 28 days. It can persist in carpets for up to 12 days even with regular vacuuming. Standard household cleaners won’t reliably kill it. You need either a bleach solution or a product specifically registered on the EPA’s List G, which certifies disinfectants that have been lab-tested against norovirus.
For a bleach solution, the CDC recommends mixing 5 to 25 tablespoons of standard household bleach (5% to 8% concentration) per gallon of water. That creates a solution of 1,000 to 5,000 parts per million of chlorine, which is strong enough to destroy the virus on hard surfaces. Use the higher concentration for areas with heavy contamination, like a bathroom floor after a vomiting episode. If you prefer a commercial product, look for the EPA registration number on the label and check it against List G on the EPA’s website. Many of these products require a contact time of 5 to 10 minutes, meaning the surface needs to stay visibly wet with the disinfectant for that long to be effective.
Wipe countertops, doorknobs, light switches, faucet handles, toilet flush levers, and any surface that gets touched frequently. During an active illness in your household, clean these high-touch surfaces at least once or twice a day.
What to Do After Someone Vomits
Vomiting is one of the most efficient ways norovirus spreads. Aerosolized droplets from a vomiting episode carry viral particles into the surrounding air, and the infection risk drops significantly with distance. Research on outbreaks has shown that people within 2 meters of a vomiting incident face substantially higher risk. One study found that children in close proximity to vomit were nearly 4 times more likely to get sick than those farther away, and 102 times more likely than children with no exposure at all.
When cleaning up vomit or diarrhea, wear disposable gloves and ideally a mask. Blot up the material with paper towels, seal them in a plastic bag, and then disinfect the entire area with your bleach solution. Don’t just clean the visible splash zone. Treat a generous radius around the site, since microscopic droplets travel farther than you’d expect. For carpet, blot and apply a bleach-safe cleaner or steam clean at high heat. Dispose of your gloves and wash your hands thoroughly afterward.
Handling Contaminated Laundry
Soiled clothing, towels, and bedding from a sick person should be handled carefully. Wear gloves when picking them up and try not to shake the fabric, which can release viral particles into the air. Wash them on the hottest water setting your machine offers and use a regular laundry cycle with detergent. If the fabric can tolerate it, adding bleach to the wash provides extra disinfection. Dry on the highest heat setting as well. Wash your hands after loading the machine, and consider wiping down the washer’s lid or door handle afterward.
Food Safety and Shellfish
Norovirus is the leading cause of foodborne illness, and it typically enters the food supply through infected food handlers or contaminated water. The single most important thing food preparers can do is stay out of the kitchen entirely while sick and for at least 48 hours after symptoms stop, since viral shedding continues well beyond the point where you feel better.
Shellfish deserve special attention. Oysters and other filter-feeding shellfish concentrate norovirus from contaminated water, and the virus can survive temperatures as high as 145°F. That means quick steaming, which is how many restaurants and home cooks prepare mussels and clams, often isn’t enough. Cook shellfish thoroughly to a higher internal temperature and for a longer duration. Fruits and vegetables should be washed carefully under running water before eating, especially items that won’t be cooked.
Protecting Yourself During an Outbreak
If someone in your household is sick, your goal is to minimize shared contact with surfaces, food, and airspace. Have the sick person use a dedicated bathroom if possible. Designate separate towels, cups, and utensils. Don’t prepare food for others while infected. These measures sound simple, but given the virus’s extremely low infectious dose, even small lapses create real risk.
Norovirus spreads most aggressively in the first few days of illness, but infected people continue shedding the virus in their stool for days or even weeks after feeling fine. Keep up your hand-washing routine and surface disinfection for at least two to three days after the last person in your household recovers.
In shared environments like offices, schools, or cruise ships, the same principles apply at scale. Frequent disinfection of shared surfaces, access to soap and water rather than just sanitizer dispensers, and keeping sick individuals away from communal spaces are the most effective strategies for containing an outbreak before it spreads through an entire group.