Norovirus: What nurses need to know

Submitted by njones on
Strain of Norovirus

What is norovirus?

Norovirus is a highly contagious virus that causes acute gastroenteritis. It is the leading cause of foodborne illness in the U.S. and worldwide, with 685 million cases globally each year. Norovirus is estimated to be responsible for approximately 200,000 deaths annually, with over 70,000 occurring among children in developing countries.

Due to its high infectivity, norovirus outbreaks frequently occur in crowded environments such as health care facilities, cruise ships, schools, and other communal settings. The virus is also resistant to many disinfectants and can survive on surfaces for extended periods.

In the U.S., there were almost double the number of norovirus outbreaks reported in August 2024 to mid-January 2025 compared to the same period the previous year. The total number of outbreaks reported in the 2024–2025 seasonal year is the second highest since 2012, surpassed only by the 2020–2021 season. The CDC identified a new strain of norovirus this year, which may be contributing to the heightened number of cases.

What are the symptoms of norovirus?

Symptoms typically consist of severe nausea, vomiting, diarrhea, and stomach pain, but can also include fever, headache, and body aches. Symptoms appear 12 to 48 hours after exposure and last for 1 to 3 days.

While norovirus gastroenteritis is typically mild and does not require medical attention, norovirus causes dehydration that can lead to serious health outcomes. Norovirus infections in health care settings often affect vulnerable populations, such as the elderly, immunocompromised, and those with comorbidities, and can result in severe illness or even death.

How is norovirus transmitted? 

Norovirus spreads primarily through:

  • Direct contact with an infected person,
  • Consuming contaminated food or water,
  • Touching contaminated surfaces and then touching the mouth or face, and
  • Exposure to aerosolized viral particles from vomiting and/or diarrhea.

Infection can occur with exposure to an infected person or to an environmental contaminant. Common foods linked to norovirus outbreaks include leafy greens, fruits, and raw shellfish, which can become contaminated with norovirus when exposed to untreated sewage and/or if handled by a sick individual. The virus has a low infectious dose, meaning even a small number of viral particles can cause illness, enabling the virus to spread rapidly in crowded conditions.

In health care settings with norovirus outbreaks, infectious norovirus has been collected from the air both inside and outside patients’ rooms, in hallways, and nurses’ stations. Norovirus can remain viable on surfaces for up to two weeks, contributing to its spread in health care environments.

Can you gain immunity to norovirus? 

Over 30,000 unique norovirus sequences have been identified as of 2022. The large number of variants and subvariants circulating simultaneously means that people can become infected with different strains over a short period of time. Research also demonstrates that, after infection, immunity to the same norovirus strain lasts less than 6 months.

Additionally, there are no vaccines against norovirus. The significant diversity between norovirus strains not only increases the feasibility of secondary infections, but also contributes to the difficulty of developing an effective norovirus vaccine.

What protections do nurses and other health care workers need when caring for a patient infected with norovirus?

Health care employers are responsible for providing a safe work and patient care environment. Multilayered infection prevention measures should be implemented to prevent norovirus exposures in all health care facilities, including:

  • Patient screening – Screen patients for norovirus-like symptoms and those who may have been exposed to infectious individuals.
  • Isolation and source control – Promptly isolate patients with suspected or confirmed norovirus in a private room using contact precautions until at least 48 hours after symptom resolution. Minimize patient movements, especially during norovirus outbreaks.
  • Hand hygiene – Wash hands frequently using soap and warm water. Note that alcohol-based hand sanitizers are ineffective against norovirus.
  • Personal Protective Equipment – Use gloves and gowns when caring for infected patients or handling contaminated materials. Use a respirator at least as protective as an N95 when there is a risk of aerosolization, such as during vomiting, flushing toilets, or changing bed linens. Use a face shield if a splashing risk exists.
  • Environmental cleaning – Disinfect surfaces with EPA-approved cleaners effective against norovirus. Bleach (1000-5000 ppm sodium hypochlorite) is recommended for environmental cleaning. Increase the frequency of cleaning and disinfection of high-traffic and contaminated areas to multiple times per day during outbreaks. Ensure that privacy curtains, if used, are changed routinely and upon patient discharge or transfer.
  • Proper waste disposal – Handle and dispose of contaminated linens and waste carefully and using precautions necessary to prevent further transmission.
  • Paid sick time – Paid sick time enables health care workers with norovirus infections to stay home without loss of pay. If the norovirus infection was sustained at work, the employer should provide paid medical removal. Sick staff should not come back to work until 48 hours after symptom resolution.