By Chip Manuel, Ph.D.

Food Safety Science Advisor, GOJO Industries

Also By Megan J. DiGiorgio, MSN, RN, CIC, FAPIC

Senior Clinical Manager, GOJO Industries

CDC data shows that cases of norovirus (aka "the stomach bug") are rising. Recently, there have been multiple elementary schools in the news after outbreaks. You may have even heard from friends who had a recent bout with the dreaded "stomach flu." This newsroom article will cover the basics about norovirus to help you prepare personally and prevent an outbreak at your business/school.

What is norovirus?

Norovirus is a highly contagious virus that causes vomiting and diarrhea – in fact, it is the world's leading cause of gastroenteritis (vomiting and diarrhea). While norovirus is sometimes referred to as the "stomach flu," it is not caused by a flu virus. (Though vomiting and diarrhea are actually less common symptoms of influenza in adults.)

What are the symptoms of norovirus?

The most common symptoms are diarrhea, vomiting, nausea, and stomach pain. These symptoms can come on suddenly. Typically, a person exposed to norovirus develops symptoms within 12 to 48 hours and recovers within one to three days. Unfortunately, you can get norovirus multiple times in your life – as there are many types of the virus. Immunity to the particular strain you had can last from months to years, depending on the strain.

How does norovirus spread?

While norovirus is the #1 cause of foodborne illness in the United States, most outbreaks are actually caused by person-to-person spread. For someone to become infected with norovirus, the germs must be ingested (swallowed). So, while it's gross to think about, the illness spreads when particles of stool or vomit from an infected person make their way into another person's mouth! How does this happen?

• By having direct contact with someone who is infected or sharing food or eating utensils with them.
• By consuming food or water that was prepared or served by an infected person who has not washed their hands properly. (That includes foods that were contaminated before or during harvest, such as oysters harvested from water contaminated with human sewage or fruits and vegetables irrigated with contaminated water.)
• By touching contaminated surfaces and then transferring the germs from your hands into your mouth, for example, while eating or touching your face. (Research has shown that the virus can be distributed over several feet by air when a person vomits, often landing on surfaces that become contaminated.) ¹

A person with norovirus can shed billions of norovirus particles in their stool and vomit, and only a few particles are necessary to infect others. So, a public vomiting incident can expose a large area (like if a child vomits in a classroom). Though you are most contagious when experiencing symptoms and during the first few days of recovery, you can infect others before symptoms start and spread norovirus for two weeks or more after you feel better.

What are common settings for norovirus outbreaks?

Outbreaks can occur anywhere that people gather indoors or in close spaces (because of how this virus spreads) and anywhere that food is served (since contaminated hands are one of the main transmission routes). Given this, the most common settings of norovirus outbreaks include long-term care facilities, schools, and restaurants. While norovirus outbreaks on cruise ships often make news headlines when they occur, that setting accounts for only 1% of all reported norovirus outbreaks, according to the CDC.

Who is most at risk from norovirus?

According to the CDC, children under 5 years of age or adults over 85 years old are more likely to have an outpatient or emergency department visit. Children often get sicker because they haven't been exposed to this virus before. These groups are more likely to seek healthcare as a result of their infection. With hospitals and other healthcare providers already burdened due to staffing shortages, any increase in illness causes an additional strain on the healthcare system.

When is norovirus season?

You can get sick with norovirus any time of the year, but most norovirus outbreaks occur during the cooler winter months, from November through April in the U.S. Unfortunately, this is the same time as other common winter viruses circulate like the flu and RSV (respiratory syncytial virus). This combination can burden our healthcare system, businesses, and schools, particularly when many businesses are experiencing labor challenges.

Why are cases surging?

Cases so far are higher than normal for this time of year but are within the range of a typical norovirus season (though there is a delay in reported cases). Several things may be causing this spike in cases – as we've seen recently with other viruses like RSV and flu. Norovirus cases in the U.S. were at historic lows in 2020 and 2021 due to pandemic precautions like social distancing, isolation, and masking. Then in spring 2022, cases came surging back as Americans began dropping those protective measures. An additional piece could be a lack of immunity. Because of those historic lows, many people haven't been exposed to the virus in several years, so they may not have immunity from the circulating strains.

Also, viruses have been behaving oddly since the COVID-19 pandemic began (see the article "Are Viruses Behaving Strangely, or Are We?"), seasons have been different, and the public behaved very differently during the pandemic (avoiding crowds/going into public places, etc.).

Norovirus prevention is key

Globally, norovirus sickens nearly 700 million each year and costs an estimated $64 billion a year, primarily through productivity loss, according to a 2016 study.² Outbreaks in schools can cause closures. Outbreaks in long-term care facilities can be deadly and sometimes last for months, according to the CDC.³ Outbreaks in restaurants can impact your reputation. On an individual level, being sick with norovirus is a miserable and memorable experience.

How can I protect myself or my family from norovirus?

Surface hygiene is essential for preventing norovirus, like for many other infectious diseases. Make sure you wash all surfaces of your hands for at least 20 seconds, particularly after going to the bathroom, before eating, and before/while/after preparing food. Disinfect frequently touched surfaces, particularly your bathroom sink/counter, and toilet. (First, be sure to clean up any vomit/feces before disinfecting the surface.)

Stay home if you're sick and wait at least two days after your symptoms resolve before going out in public or visiting family/friends. Don't prepare food for others while you are sick and wait at least two days after symptoms stop. If someone in your home is sick, isolate them to their own room and bathroom, if possible. If you can't isolate them, clean the shared surfaces they touch after use (like in the bathroom).

How can I prevent a norovirus outbreak at my business/facility or school?

We've covered that norovirus is highly contagious, but because of the structure of the virus (non-enveloped) it is also hard to kill – which makes this virus a particularly challenging one to combat. It can remain infectious on countertops, serving utensils, and other surfaces for up to two weeks. It can remain infectious on foods even at freezing temperatures and until heated above 140°F, according to the CDC. ⁴

• Universally, regular hand and surface hygiene are critical precautionary measures. Focus regular touchpoint disinfection on restrooms. Encourage sick employees to stay home by adopting sick leave policies.
• Long-term care: focus frequent disinfection on high-traffic and resident areas. Clean and disinfect shared equipment between residents. During outbreaks of norovirus or gastroenteritis, increase the frequency of cleaning and disinfection of residential areas and frequently touched surfaces (e.g., increase unit level cleaning to twice daily to maintain cleanliness, with frequently touched surfaces cleaned and disinfected three times daily). Use EPA-registered products with label claims for use in healthcare.

• Food settings: ensure employees are not reporting to work while sick with foodborne illness (such as norovirus) through employee wellness screenings and adopting sick leave policies. Emphasize frequent and proper hand hygiene as a major aspect of your food safety plan. Minimize bare-hand contact with food. Disinfect high-touch surfaces regularly, like restroom door handles, handwash sink faucet handles, and restroom stall latches.
• K-12 schools: focus on frequent disinfection on shared surfaces in restrooms, cafeterias (including where food is prepared/served), school nurse/clinic (where sick children may congregate), and gyms/locker rooms. Ramp up disinfection during illness outbreaks.

What products are critical to preventing outbreaks at my business?

• Make sure your surface sanitizer and disinfectant are effective against norovirus. Many EPA-registered food-contact, no-rinse surface sanitizers on the market are not approved to kill norovirus. Be sure to examine the product's label to determine what pathogens it is effective against, and always follow the label use instructions. (To learn more about how important formulation is when it comes to product performance against norovirus, read this Q&A from North Carolina State University about new research.)
• Select ready-to-use surface sanitizers and disinfectants with short contact times (e.g., a minute or less for organisms of interest) to help increase staff compliance with enhanced disinfection protocols and in turn, help reduce the risk of an outbreak within your facility. Plus, it saves your staff valuable time. Follow the manufacturer's recommendations for application and contact times.
• Choose products that limit your staff and students'/guests' exposure to harsh fumes, by choosing products rated by the U.S. Environmental Protection Agency (EPA) as category IV (very low toxicity). Norovirus is hard to kill, but that does not mean you need to bring in harsh chemicals like bleach. (Watch out for higher toxicity products with precautionary statements like "Caution," which may require handwashing after use and personal protective equipment, such as gloves, gowns, and eye protection during use.)
• Body fluid spill kits are handy for quick clean-up of body fluid incidents in restaurants, school buses and gyms/athletic facilities, and healthcare facilities. Comprehensive body fluid spill kits will include a complete set of instructions so team members know how to properly respond to body fluid incidents, including safe disposal procedures. A fully stocked body fluid spill kit will include everything team members need, reducing the risk of an outbreak with the ability to respond as quickly as possible.

For more information on norovirus, visit the CDC norovirus page. Businesses can check with their local or state public health agency for norovirus prevention guidance

Worry-free and effective solutions are available:

• PURELL^® Multi - Surface Sanitizers, Disinfectants, and Wipes are EPA-registered, safe for most hard surfaces (spray is also safe on most soft surfaces), and quickly kill 99.9% of viruses and bacteria, including norovirus (spray kills in 30 seconds), the flu virus, and human coronavirus (COVID-19). They earned the EPA's lowest allowable toxicity rating (Category IV), so they don't contain harsh chemicals or fumes and don't require gloves, handwashing, or rinsing after use – even on food-contact surfaces. PURELL® surface sprays are certified for the EPA's Design for the Environment (DfE) as part of the EPA's Safer Choice program. 

PURELL® surface sanitizers and disinfectants are U.S. EPA-registered and approved to kill norovirus on hard surfaces. Our goal is to provide products that are the best in the market, and towards that goal we conducted additional efficacy studies outside of the U.S. EPA requirements which demonstrated the efficacy of PURELL® surface spray products against human norovirus when used in realistic situations in accordance with label directions. ⁵

Interested businesses should contact their GOJO distributor.

1. Tung-Thompson G, Libera DA, Koch KL, de los Reyes FL III, Jaykus L-A (2015) Aerosolization of a Human Norovirus Surrogate, Bacteriophage MS2, during Simulated Vomiting. PLoS  ONE  10(8):  e013427
2. Bartsch SM, Lopman BA, Ozawa S, Hall AJ, Lee BY (2016) Global Economic Burden of Norovirus Gastroenteritis. PLoS ONE 11(4): e0151219. https://doi.org/10.1371/journal.pone.0151219
3. Centers for Disease Control and Prevention, "Common Settings of Norovirus Outbreaks." https://www.cdc.gov/norovirus/trends-outbreaks/outbreaks.html Accessed Feb. 10, 2023.
4. Centers for Disease Control and Prevention, "Preventing Norovirus Outbreaks." https://www.cdc.gov/vitalsigns/norovirus/index.html Accessed Feb. 8, 2023.
5. Faircloth, J., Goulter, R.M., Manuel, C.S., Arbogast, J.W., Escudero-Abarca, B., Jaykus, L. The Efficacy of Commercial Surface Sanitizers against Norovirus on Formica Surfaces with and without Inclusion of a Wiping Step. Applied and Environmental Microbiology. Aug. 25, 2022. https://journals.asm.org/doi/10.1128/aem.00807-22