Norovirus spreads very easily and quickly through several main routes:

• Direct contact with infected people: Touching or caring for someone who is sick with norovirus, sharing food, utensils, or cups with them can transmit the virus

• Contaminated food and water: Norovirus can contaminate food if an infected person handles it with bare hands, if food is placed on contaminated surfaces, or if it is grown or washed with contaminated water (e.g., oysters, fruits, vegetables). Drinking or recreational water can also be contaminated by sewage leaks or improper treatment

• Contaminated surfaces and objects: The virus can survive on surfaces for days or weeks. Touching surfaces or objects contaminated with norovirus particles and then touching your mouth can cause infection. Vomit or diarrhea from infected people can contaminate surfaces and spread the virus

• Airborne particles from vomiting: Tiny droplets of vomit can spray through the air, landing on surfaces, food, or being inhaled, leading to infection. Vomiting is a particularly effective mode of transmission and can cause outbreaks in close settings like restaurants

People are most contagious when they have symptoms, especially vomiting, and remain contagious for at least a few days after recovery. In some cases, they can still spread the virus for two weeks or more after feeling better

. Good hand hygiene with soap and warm water is critical to prevent spread, as alcohol-based sanitizers are not effective against norovirus

. In summary, norovirus spreads primarily through fecal-oral transmission via direct contact, contaminated food or water, contaminated surfaces, and airborne particles from vomiting. Its high contagiousness and environmental stability make it easily transmissible in community and close-contact settings.