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It was 11 p.m. and I had just fallen asleep when I heard a cry from my 4-year-old son’s room. I headed downstairs to find a trail of vomit on the carpet and up the stairs, as he tried to make his way up to my bedroom. The next few hours were a blur as I rushed him back and forth to the bathroom. The second time he got sick, he vomited directly into my hands, onto my robe, in my hair. As frantically as I worked to scrub my hands and face with soap and water and get all the clothes and bedding into the laundry, I knew I would be the next person to experience norovirus in the house.
How could I be certain? The spread of norovirus is quick and efficient.
Many factors contribute to its spread:
- Infectious dose: With just 100 (or fewer) viral particles, norovirus can infect the next person. Considering there is somewhere between 1-100 million particles in just 1 milliliter of vomit, only a small amount is needed to pass on the infection.
- Stability in the environment: Norovirus is hardy due to its hard protein shell. It is resistant to extreme temperatures, lives for days to weeks, and is resistant to many common cleaning agents, including alcohol-based hand sanitizers. If an infected person vomits in the bathroom (or elsewhere), every contaminated surface must be cleaned with a disinfectant (typically bleach) that can effectively kill norovirus.
- Transmission routes: Norovirus spreads through the fecal oral route, aerosolized particles from vomiting, and any close contact with viral particles on a countertop or doorknob.
As predicted, about 40 hours later — the incubation period is 12-48 hours, allowing the virus to spread rapidly in crowded locations — I became ill. Despite having had norovirus in the past, immunologic memory is often short-lived compared to some other viruses, and prior memory from a different strain may not be protective. My daughter’s symptoms followed 6 hours after mine, likely from the carpet I couldn’t sanitize, the doorknob I didn’t scrub well enough, or simply from playing with her brother the next day, who is still learning hand hygiene. Even if symptoms quickly resolve, people continue to shed virus. This means that one ineffective post-restroom hand wash the day (or week) after illness can lead to ongoing spread.
Managing the Symptoms
My son was more miserable than my daughter, asking for tummy medicine or a glass of water. I had no anti-emetics in the cabinet and his dry red lips showed his dehydration. I told him to take one sip from the cup next his bed to begin rehydrating. Unfortunately, he gulped down about 6 ounces, which he promptly vomited back up. We changed tactics to a small medicine cup with an ounce of Pedialyte and then set a timer for 15 minutes. Once he kept that down, we continued with small ounce cups every 5-15 minutes.
Age-specific oral rehydration (ORT) therapy is best done with a fluid with salt and sugar — Pedialyte, a diluted sports drink, or even diluted apple juice. Anti-emetics may help with dehydration, particularly if a patient is unsuccessful with ORT at home. Protocols in medical settings that include early use of medications like ondansetron (Zofran) coupled with ORT demonstrate shorter visits and decreased use of IV fluids. Similarly, antidiarrheal medications may help reduce fluid losses after the acute illness while the intestinal track begins to heal. Some patients may be able to tolerate a normal diet within a day, while others may have post-infectious symptoms that require diet modification while the gastrointestinal (GI) tract is recovering.
Sharing this guidance with patients, or parents of patients, can guide their recovery.
Why Are We Seeing More Cases This Year?
Our home was just a microcosm of the current environment. In January 2025, the rate of norovirus test positivity reported by a U.S. lab network was more than twice as high as last season, and may be peaking earlier than prior seasons. This is attributed to the presence of a new strain, GII.17[P17]. In seasons when a new strain circulates, the country can see a large increase in cases compared to typical seasons, spiking earlier than usual.
Staying Safe in the Hospital
Norovirus spreads through households, in crowded settings like daycares and cruise ships, through contaminated food, and unfortunately, at the workplace — including the hospital. Recall that only 100 particles of virus are needed to spread to another person.
Take this scenario: You’ve just examined a baby dehydrated from norovirus and adjusted their diaper, which is teeming with virus. After the visit, you use alcohol-based hand rub instead of soap and water. Particles survive on your hands. You grab a handful of M&Ms from the hospital break room candy bowl before the next patient. Not only are you likely to become sick, but with the candy bowl contaminated, the next few employees to grab handfuls of M&Ms are likely to become symptomatic as well.
How do you stop spread through the hospital?
- Practice meticulous hand hygiene. This is essential. Wash hands with soap and water instead of alcohol-based hand rub for a full 20-30 seconds after caring for patients with GI illness, before eating, after using the restroom, and before preparing food.
- Identify patients with gastrointestinal symptoms and follow your hospital’s practices for testing and isolation. Isolation practices can be symptom-based, and testing can be used to identify trends in your community or outbreaks in your institution that may alter your infection prevention practices.
- Follow and share food safety guidance. Eat and drink only in non-patient care areas. Avoid finger foods or shared snacks. Have hand hygiene available in hospital break rooms.
- Pay attention to your personal protective equipment. Use standard precautions to protect yourself whenever changing a diaper. If you mask during patient care, change your mask after caring for a patient who has gastroenteritis or is actively vomiting, as it can be contaminated.
- Ensure your care areas are easy to clean. Minimize clutter and have disinfectants readily available with a norovirus kill claim.
- Stay home when sick. Ensure your practice has a robust sickness policy that supports employees staying home when sick. If possible, have employees report GI symptoms to understand if you have spread in your hospital.
Avoiding Norovirus Is Possible
Remarkably, in our household of norovirus sufferers, my husband remained unscathed — or at least asymptomatic. How? He recalled my vivid descriptions of norovirus’s stealthy spread in the workplace: bowls of popcorn and bags of Skittles, contaminated by a single unwashed hand, infecting an entire group. Motivated by this knowledge, he diligently practiced impeccable hand hygiene, ran endless loads of laundry, and obsessively sanitized every surface we touched.
His efforts served as a reminder that while norovirus is notoriously contagious, its spread is not inevitable. With vigilance and prevention, even norovirus can be contained.
Lori Handy, MD, MSCE, is associate director of the Vaccine Education Center and an attending physician in the Division of Infectious Diseases at the Children’s Hospital of Philadelphia (CHOP). She is also an assistant professor of Clinical Pediatrics at the Perelman School of Medicine.