Close to 50 million Americans traveled for Thanksgiving last year. If you’re on a plane for the holidays, here’s some tips on how to avoid getting sick.

For many, the start of the holiday season means not only family and food, but also getting on a long-distance flight.

Unfortunately, traveling through large airport security lines and getting stuck on crowded airplanes for hours at a time is a great recipe for getting sick.

Since the holiday season coincides with the start of flu season in the Northern Hemisphere, it can also mean travelers have to kick off Thanksgiving or other winter holidays while also fighting off the virus.

Travelers afraid of germs were likely not helped by the news that listeria was reportedly detected at a catering facility for American Airlines and other airlines.

According to the Gate Gourmet, which runs the catering kitchen, the bacteria was found in a drain at the facility, and not on food preparation areas.

“As part of routine inspections, we identified traces of listeria in non-food contact areas, primarily floor drains, at our LAX unit,” a spokeswoman for the Gate Group, which runs Gate Gourmet, said in a statement. “Immediately and in accordance with our protocols, all floor drains and surrounding areas were immediately and aggressively treated. Independent food safety agencies have confirmed that our unit adheres to food safety regulations and we are not aware of any instance where passengers are put at risk.”

While it may be impossible to avoid all viruses and bacteria during holiday travel, there are some key steps you can do to help ensure you don’t spend the holidays sick in bed.

Health officials say the best way to protect yourself during flu season is to simply go to your doctor to get a flu shot.

The vaccine is recommended for virtually everyone over the age of 6 months. The respiratory seasonal flu virus mainly spreads via “droplets made when people with flu cough, sneeze or talk,” according to the Centers for Disease Control and Prevention (CDC).

These droplets can infect people as far as 6 feet away.

“First and foremost, get your flu shot,” Dr. William Schaffner, an infectious disease expert from Vanderbilt University Medical Center, told Healthline.

“That’s terribly important,” he added, “because when you’re traveling in crowds, large numbers of strangers encountered in airplanes, airports wherever you’re going whenever you visit your relatives… There are ample opportunities to get infected with the influenza virus.”

The vaccine isn’t foolproof. But even if you start to exhibit symptoms, they’re usually less severe than if you didn’t get a flu shot.

The listeria detection in Los Angeles highlights the risks people can face with foodborne illness while traveling.

In some cases, the risk comes from passengers themselves.

They may arrive to a flight already sick, which means they risk infecting other passengers or contaminating surfaces.

On one flight, 26 passengers had to cope with serious symptoms of food poisoning while on a Qantas flight, according to reports.

Dr. Louis J. Morledge, a general specialist in internal medicine specializing in travel medicine at Lenox Hill Hospital in New York, said there are simple measures people can take to avoid getting sick via contaminated surfaces.

One of the main prevention measures is simply keeping your hands clean.

“Do your best to avoid touching your hands to your mouth, nose, and eyes, because these are portals of entry for infection,” Morledge told Healthline. “You should wash your hands regularly, preferably with hot water and soap.”

He also said using a sizeable amount of hand sanitizer can do the trick. About a quarter-sized amount can work in a pinch if you can’t get up easily to use the restroom.

“The idea is for that practice to occur often,” he said of handwashing. “Especially after using a restroom or before meals or after you’ve been in a public place, you may want to be extra careful to be sure you do that, because bacteria can linger on surfaces… Whether you talk about doorknobs, whether you talk about desktops and tray tables, etc.”

For those concerned about getting sick from the food itself, Schaffner said there’s some key steps people can take — although he added that the risk is minimal on domestic flights.

Schaffner advises sticking with hot food and drinks that are either boiled or in factory-sealed containers.

While these tips are mainly for people traveling in countries with less strict food standards than the United States, worried travelers can adopt them when traveling locally as well.

“When you are in the developing world, there’s an old rule. Avoid salads,” Schaffner said. “Regarding everything else, make sure before you eat it, it’s heated.”

According to the CDC, meats like hot dogs and cold cuts should be cooked to 165ºF (74ºC) to kill bacteria like listeria.

One familiar travel nightmare is boarding the plane, only to find that you’re next to a sick passenger who’s coughing and sneezing.

Morledge said it’s possible that using an air vent located above passenger seats can help stop the spread of a disease via coughing and sneezing.

“The vents are somewhat valuable,” he said. “It will circulate air… If there is disease around you, you are circulating things” and can disrupt the spread of disease.

Schaffner said there’s another step passengers can take if a neighbor is clearly sick.

“Travel with facial tissue, Kleenex,” he said. “If there is someone out there coughing in your vicinity and they’re not covering themselves, with a smile and pleasant suggestion offer them the Kleenex and say, ‘Perhaps this would help?’ It certainly would help protect us.”

Schaffner, who was getting over his own travel-acquired virus, said it may be a little uncomfortable, but “giving them a hint and help with a nice smile” can go a long way to keeping the peace with your neighbor and staying healthy.