As the norovirus cases continue to spread in the U.S., you can't rely on hand sanitizer alone to protect you, experts warn.
Norovirus causes gastrointestinal symptoms like nausea, vomiting, diarrhea and stomach cramps. It can spread quickly in places where people are sharing living spaces, such as on cruise ships, and outbreaks tend to spike at this time of year.
Cases of norovirus, previously called the “winter vomiting disease,” do typically rise at this time of year, Dr. Craig Wilen, associate professor of laboratory medicine and immunology at the Yale School of Medicine, tells TODAY.com.
There are around 2,500 norovirus outbreaks reported every year, the Centers for Disease Control and Prevention says, with most of those outbreaks occurring between November and April. But right now, the country is seeing even more norovirus activity than usual, according to the most recent CDC estimates.
“This year, the number of reported norovirus outbreaks have exceeded the numbers that we’ve seen recently and in the years before the pandemic,” a CDC spokesperson told TODAY.com earlier this month.
Wilen agrees: "We are seeing a lot of outbreaks now, so it's greater than the past couple years," he says, but he adds that the numbers we're seeing now aren't completely out of the ordinary.
So, what's the best way to keep yourself safe and your home norovirus-free? Unfortunately, one expected tool — hand sanitizer — simply isn't as effective against this particular pathogen.
How nororvirus spreads
Norovirus is very contagious, the CDC warns, and it spreads from person to person quickly and easily.
Specifically, it spreads through viral particles contained in feces and vomit. This route is what's known as "fecal-oral transmission," says Wilen, whose research focuses specifically on how noroviruses spread.
There are two main ways norovirus particles go from person to person, Wilen says. They can spread via direct human contact. Or the virus can spread through fomites, "which are basically any contaminated object where the virus can get on," he explains.
Those viral particles can contaminate food, water and surfaces that can then go on to infect other people. Essentially, viral particles from feces or vomit get onto someone's hand or land on a surface, such as kitchen countertops or toilet handles, which someone else then touches. Having explosive vomiting or diarrhea — or not closing the lid on the toilet when flushing — disperses the particles even further, Wilen adds.
Once on a surface, "the virus can be stable for days, if not longer," Wilen says, "and then someone can touch that surface or eat something that has the virus on it and get infected that way."
Unlike some other viruses, norovirus does not spread through the air, Wilen notes, so wearing a mask won't prevent you from getting infected.
While people with norovirus are most contagious when they have symptoms (especially vomiting), the CDC explains, they can continue to spread the virus for two weeks or even longer.
It's also possible to have very mild symptoms or no symptoms at all while infected with norovirus, Wilen says. "They can shed the virus asymptomatically, and it's likely those people that are helping to initiate these outbreaks," he explains.
Does hand sanitizer work against norovirus?
Hand sanitizer is simply not as effective against norovirus as it at killing other pathogens due to the virus's firm shell, Dr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center, toldTODAY.com recently.
There are two major categories of viruses, Wilen explains: enveloped and non-enveloped.
Enveloped viruses, like influenza and coronaviruses, are encased in a lipid bilayer (yes, the one you learned about in high school biology class). "It's the lipids that are really susceptible to ethanol-based hand sanitizers," Wilen explains, which break down that outer layer and inactivate the virus.
Norovirus, on the other hand, is a non-enveloped virus. It’s encased in a hard, protein-based shell called a capsid. That shell is "pretty environmentally stable," Wilen says, "and that's what makes it relatively resistant to ethanol-based hand sanitizers."
Washing your hands with soap and water is a much more effective way to protect yourself from norovirus. That's because "soap is a detergent, and it can dissolve and break apart the capsid and inactivate the virus pretty efficiently," he explains. Washing your hands both inactivates the virus and flushes it off your skin.
While there is research to suggest that hand sanitizers can be "somewhat effective," Wilen notes, "soap is definitely the way to go."
So, while you can use hand sanitizer in addition to washing your hands, the CDC says, hand sanitizer is not an effective replacement for hand-washing when it comes to preventing norovirus.
How to properly protect yourself from norovirus
Because hand sanitizer isn't as effective against norovirus, you'll need to properly wash your hands in order to protect yourself.
According to the CDC, that means:
- Wash your hands with soap and water.
- Wash your hands for at least 20 seconds at a time.
- Wash your hands frequently.
You should always take care to wash your hands properly after using the toilet or changing diapers, before giving yourself or someone else medicine as well as before eating, preparing or handling food, the CDC says.
Properly handling food and quickly cleaning up bathroom areas after someone has diarrhea can also help prevent the spread of norovirus.
Luckily, norovirus is susceptible to most household cleaners, especially bleach-based cleaners, Wilen says. Bleach wipes are very effective against norovirus, he says, adding that his research team uses bleach as their "primary activation agent" when growing norovirus in the lab.
Unlike many other viruses, there is no vaccine or drug treatment available for norovirus, Wilen says. So knowing how to protect yourself and prevent the spread is key to keeping this virus in check.
