Beware of a sniffling flight attendant.

Flight attendant during the safety demonstration
Credit: Swell Media/Getty Images

Staying healthy on a flight is one of the top priorities for frequent travelers. One person's sniffle, cough, or sneeze can send a lot of other passengers reaching for the hand sanitizer.

But a study published on Monday in the Proceedings of the National Academy of Sciences claims that passengers are not likely to contract viruses — mainly the flu virus — from other passengers on flights who are not seated very close to them.

According to the study, if a passenger is seated more than 1 meter, or 3.3 feet, away from you, chances are you’ll be able to get off the flight disease-free.

Researchers from Emory University, the Georgia Institute of Technology, and Boeing flew on 10 different cross-country flights in order to observe the risks of infection. Most flights ranged from three and a half to five hours, and planes were close to or at full capacity.

In order to track infection risk, researchers tracked passenger movement through an iPad app, simulating the spread of flu virus from a passenger seated in the mid-cabin (seat 14C). They noted how often passengers interacted with each other as well as how often they left their seats — which are the two main causes of the spread of infection on flights. They also collected samples of commonly touched surfaces.

Surprisingly enough, those surfaces contained almost no evidence of 18 common respiratory viruses, but not everyone on the flights got away without being infected. Analysis showed that people within two seats on either side, as well as one row in front and behind, of the original infected passenger had an 80-percent chance of becoming sick.

However, when it came to other passengers on the flight, the risk of infection dropped dramatically to 3 percent.

The study also noted the possibility of an infected crew member being on a flight — which would put many more passengers at risk, since they would undoubtedly move about the cabin and interact with more passengers. The study confirmed that sick crew members should either stay home or take medication to limit coughing and sneezing. “Movements of passengers and crew may facilitate disease transmission,” the study notes.

For passengers, however, the best way to avoid infection is to avoid touching your eyes, face, and shared surfaces. If you are sitting next to a sick passenger, try to face away from them and use hand sanitizer.

In addition, the study found that people sitting in window seats who did not get up during the flight were at less of a risk.

It should be noted that the study does not address flights shorter than three and a half hours, or planes with more than one aisle. Nor does it apply to severe infectious diseases like the measles.

"Our model is not applicable to other aerosol-transmitted diseases, such as tuberculosis (18), varicella, and measles (19). Our model assumes omnidirectional transmission and does not take into account seat backs as barriers. Thus, our simulation results may be overestimating risk of direct droplet-mediated transmissio," the study says.

Plus, there is still a chance of passengers getting sick in the airport or on the tarmac, before they even set foot on the plane. So, for the best protection, everyone should take their vitamins and keep the hand sanitizer and cough drops ready.