Looking forward to Sunday’s Super Bowl party with friends? Enjoy the snacks and the big game, but make sure you don’t pick up the flu or another viral illness from a fellow partygoer.

Experts say it’s easier for viruses to spread when groups of people gather in enclosed spaces—as millions will be doing in living rooms across the U.S. on Super Bowl Sunday.

"Winter, when people are cooped up in close proximity more often, is the time of year when you're most at risk of catching many common respiratory and gastrointestinal viruses,” says Marvin M. Lipman, M.D., Consumer Reports’ chief medical adviser. “A big get-together like a Super Bowl party just increases your chances of catching an illness, such as the common cold, norovirus, or influenza, from someone who’s a carrier or who hasn’t started showing symptoms yet."

In fact, a 2016 study in the American Journal of Health Economics found that when cities sent their National Football League teams to the Super Bowl, they saw an 18 percent increase in flu deaths in older adults—compared with cities whose NFL teams didn’t make the championship game.

The researchers, who looked at 30 Super Bowl seasons, also found that the number of deaths was highest when the game coincided with the peak of flu season (thought to be about now) and when that year’s flu was more aggressive (like the H3N2 strain that has predominated so far this flu season).

So how to stay healthy and enjoy the game? Try this plan. 

Stay Healthy at the Party

If you’re a guest: Avoid reaching directly into communal bowls of food, advises Jeffrey Pellegrino, Ph.D., M.P.H., a member of the American Red Cross Scientific Advisory Council and professor and program director of health sciences at Aultman College in Canton, Ohio. That includes chips and other finger foods.

If there’s no serving utensil, skip the item or politely ask the host for one, Pellegrino says. Don’t dip chips directly into that bowl of onion dip—serve yourself an individual portion on your own plate.

Don't share your drinks or food with anyone else. Hang onto your beverage; if you have to put it down, place it out of the way so that no one else mistakes it for theirs—if in doubt, grab a clean glass.

And if, during the game, you feel an urge to high-five a friend, opt for a fist-bump—which brings less person-to-person contact than a palm-slap—instead, Pellegrino says.

“Those surfaces that you’re probably going to touch your face with, like your hands or fingertips, are the ones you want to avoid getting contaminated,” he says. Better yet, stick to cheering during the Super Bowl party.

If you’re the host: Make sure every dish has serving utensils to reduce the likelihood that guests will use their hands to help themselves. When possible, provide single portions of food, such as individual snack packages of chips, popcorn, and pretzels, suggests Maxine Siegel, R.D., who heads CR's food-testing lab. You can also set out small, disposable snack cups of these, or foods such as dips and nuts.

If you're serving items that feed multiple guests, like a six-foot party sub sandwich, precut them so that guests don't have to handle the food as they cut their own slice.

Have a way for people to label their drinking glasses. For instance, you can place masking tape and markers near the glassware so that guests can write their names on a piece of  tape and attach it to their glass.

In the bathroom, provide paper towels for people to dry their hands, instead of communal hand towels. And have plenty of tissues available in every room where guests may be.

If you’re sick: Stay home. Keeping yourself away from others is the surest way to avoid infecting anyone else with the flu, or other bugs. The tips above can help reduce the chance of many viral ills, but recent research suggests that the flu may be primarily transmitted through the air—rather than by touching flu-contaminated surfaces or in the moisture droplets we expel during coughs and sneezes, says Michael Osterholm, Ph.D., M.P.H., professor of public health at the University of Minnesota and director of the Center for Infectious Disease Research and Policy.

A study published in January in the Proceedings of the National Academies of Science, for example, found that college students with flu shed contagious virus through their breath—no coughing or sneezing necessary, according to Donald Milton, M.D., professor of environmental health at the University of Maryland School of Public Health in College Park and one of the study’s authors.

And even if you’re just feeling a bit under the weather, or are getting over the flu and think you’re no longer contagious, it’s probably best to cancel your game day plans and watch from the comfort of your own couch. As Milton points out, some people with the flu can have very mild—or no—symptoms, but research suggests they can still spread the virus to others.  

If you’ve got the flu, even if you’re not coughing and sneezing, you’re probably infectious and your friends will appreciate it if you don’t expose them,” Milton says. According to the Centers for Disease Control and Prevention, people with flu can remain contagious for five to seven days after they first experience symptoms.