Norovirus, a highly contagious virus that causes acute gastrointestinal illness, is making its presence known across the United States. Symptoms typically begin 12 to 48 hours after exposure and last one to three days and include diarrhea, vomiting, nausea, and abdominal pain.

During the last half of 2024, the Centers for Disease Control and Prevention (CDC) reported close to 500 norovirus outbreaks, a significant increase when compared to the same time period in 2023. These outbreaks have occurred in health care facilities, restaurants, schools, and cruise ships and are continuing to occur in 2025. Norovirus is also the leading cause of foodborne illness outbreaks in the United States, but it is not simply a foodborne or food contamination issue. In fact, norovirus transmission is more complex—and therefore often underappreciated in its impact on human health, including patients and health care workers.

The vulnerability of health care settings to norovirus.

Let’s look at some of the reasons why norovirus represents a particular problem in health care. Health care settings are particularly vulnerable to norovirus outbreaks because of the close proximity between patients, frequent contact with health care workers, and the presence of vulnerable populations such as the elderly and immunocompromised individuals. A symptomatic nurse or health care worker can unknowingly spread the virus to multiple patients through direct contact or via contaminated surfaces. Illness among those responsible for food handling and preparation can also be involved in transmission.  To that end, in health care settings many have a role in prevention.

Main challenges in preventing and controlling norovirus in health care involve how norovirus is transmitted, difficulties in removing it from the environment and from the hands of health care personnel, consistent application of basic infection prevention practices, surveillance and reporting of illness, and rapid response when outbreaks are suspected or recognized.

Norovirus transmission

One of the most unrecognized aspects of managing norovirus is its low infectious dose—as few as 10 to 100 viral particles can cause infection. This means that even a few viral particles on surfaces or hands can result in transmission. Infected individuals can shed billions of viral particles in their stool and vomit, even after they recover from symptoms. Vomiting results in aerosolization of these particles and surrounding areas may be grossly contaminated, even when not visibly soiled. Viral shedding can continue for up to two weeks, though individuals are most contagious while symptomatic. This high shedding rate, combined with the minimal infectious dose, makes norovirus extremely difficult to control, especially in health care settings.

Environmental and hand contamination

The composition of the virus itself makes environmental infection control as well as hand contamination more difficult. Unfortunately, norovirus is resistant to some commonly used disinfectants. Disinfectants effective against norovirus are listed by the Environmental Protection Agency (EPA) and must be labeled as effective against human norovirus or feline calicivirus, a surrogate virus used for testing disinfectant efficacy. Disinfectants appropriate for use to address norovirus include sodium-hypochlorite, hydrogen peroxide, and quaternary ammoniums combined with alcohol. Ensuring effective products are used by environmental services personnel as well as others assisting with environmental cleaning and disinfection is critical to preventing and controlling norovirus. Unlike many other viruses, norovirus lacks a lipid envelope, which makes it resistant to alcohol. Most alcohol-based hand rubs only partially inactivate norovirus and do not reliably prevent transmission. Mechanical removal through performance of handwashing with soap and water physically removes viral particles from the skin. This is why handwashing may be recommended instead of alcohol-based hand rubs in some circumstances, and in particular when dealing with norovirus.

Infection prevention and control basics

Use of standard precautions that prevent contact with patient body fluids is a basic infection prevention activity. Use of personal protective equipment to prevent contact with body fluids and handwashing to remove contamination and prevent movement of the virus to other surfaces, patients, or self are paramount. Early identification of a patient with gastrointestinal symptoms and initiation of isolation until the etiology is identified is also a basic infection control practice and relies upon the assessment of nursing personnel and their rapid response.

Surveillance and reporting of illness

Prompt reporting of patient and employee illness helps prevent transmission and identify potential outbreak situations. Contacting infection control departments when patients are symptomatic as well as communicating health care personnel illness to employee/occupational health departments help maintain rapid surveillance and response efforts. Obtaining samples for testing should be performed in collaboration with infection control, public health, and microbiology.

Rapid outbreak response

A single case of norovirus is a threat to patient and health care personnel safety. Rapid recognition of a case and communication to health care providers, infection prevention and control, environmental services, and local public health can make the difference between a single case and an outbreak and can prevent serious health outcomes among vulnerable patients.

Nursing considerations for prevention and response.

Given this background about norovirus, there are specific actions that nurses can take to improve prevention and response:

Promptly report gastrointestinal symptoms experienced by patients to the infection prevention and control department and partner to minimize risk to other patients and health care personnel. This communication should also include environmental services in the event a change is needed in the disinfectant used in a given patient care area.
Consistently use standard precautions including use of gloves and other barrier precautions to prevent contact with patient body fluids. In the event the patient is vomiting, recognize the risk of vomitus aerosolization and initiate additional personal protective equipment use (e.g., mask as a barrier) as needed.
Recognize the importance of soap and water handwashing when dealing with norovirus. Communicate to others when patients are experiencing gastrointestinal symptoms so handwashing can be performed by all of the patient care team.
Facilitate notification of the facility quality and infection control teams so they are aware and able to ensure rapid implementation of heightened interventions and public health communication.
Stay home when experiencing gastrointestinal symptoms and share information regarding illness with individuals responsible for occupational/employee health.
Be aware of illness present in local communities. Remember that nurses are consistently recognized as the most trusted health care professional and patients and others may come to you with questions. Further, patients and others may understand your infection control practices as a model so make sure you are consistently applying best practices.

For more information from the CDC about norovirus for the public and clinicians, click here.

Ruth Carrico, PhD, FNP-C, CIC, FSHEA, FNAP, FAAN, is an adjunct professor in the Division of Infectious Diseases at the University of Louisville School of Medicine and a board certified family nurse practitioner. She has worked in the field of infection prevention and control for more than 30 years and is also board certified in infection prevention and control. Her research and clinical practice focus on disease prevention in all settings where care is delivered and involves public health and care of vulnerable populations. Ruth’s last post for this blog was “The Critical Role of Nurses in IV Fluid Conservation.”

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