If you want to avoid catching a cold or the flu during your next plane trip, your best bet is to book a window seat. Oh — and don’t get up during the flight.
The study also found that airplane cabins are not quite as efficient at spreading germs as we’ve been told in the past. The conventional thinking of public health officials has been that passengers within two rows of a person with a respiratory infection are at significant risk of getting sick. This new study reports that the infectious zone in a plane is much smaller.
According to the study, your probability of catching a respiratory infection from an infected passenger is only about 3 percent — unless that person is seated within about three feet from you (two seats to your right or left, or in the row directly in front or behind you). Then your chance of getting sick jumps to 80 percent.
Frequent flyers shouldn’t panic, though. That 80 percent is a relative risk. In absolute-risk terms, it means that about one additional person will get ill for every infected person on the plane, the study says.
If your flight attendant is infected, however, then your chance of becoming infected increases no matter where you’re seated, although that risk is higher if you’re in the aisle or middle seat.
On a flight with an infectious crewmember, an average of 4.6 passengers would subsequently become ill, the study found.
For the study, a team of researchers from Emory University and the Georgia Institute of Technology painstakingly observed — and logged — the behavior and movements of 1,540 passengers and 41 crewmembers on 10, single-aisle transcontinental U.S. flights.
The data revealed some interesting patterns. “We now know a lot about how passengers move around on flights,” explains Vicki Hertzberg, a biostatistician at Emory University, in a released statement. “For instance, around 40 percent of passengers never leave their seats, another 40 percent get up once during the flight, and 20 percent get up two or more times.”
“Proximity to the aisle was also associated with movement,” she adds. “About 80 percent of passengers in aisle seats got up during flights, in comparison to 60 percent of passengers in middle seats and 40 percent in window seats. Passengers who leave their seats are up for an average of five minutes.”
The most common reason people left their seat was, not surprisingly, to use the lavatory, followed by checking the overhead bin.
The data also revealed that people sitting in the aisle seats had the greatest number of contacts with other passengers (an average of 64 per flight), followed by those in the middle seats (an average of 58). Contacts were much lower (an average of 12) for people in the window seats.
Using that movement data, as well as information about air circulation patterns inside planes, Hertzberg and her colleagues then modeled how a droplet-transmitted pathogen might spread from an infected passenger seated mid-cabin (14th row, aisle seat) during those flights.
The model indicated that a person is unlikely to spread their illness to people who are further than a row away.
The same wasn’t true for crewmembers, however, because of their more fluid movements throughout the cabin. “An infectious flight attendant can generate several infections; thus, it is imperative that flight attendants not fly when they are ill,” Hertzberg and her colleagues write.
The researchers also collected 228 air and surface samples from areas on the planes where infectious microbes were most likely to be found.
“Although eight flights were during influenza season in the northern hemisphere, all results were negative,” the researchers write. This somewhat surprising finding may be due to the fact that only one person on all the flights was observed to be coughing and that all hard, interior surfaces on these particular planes were disinfected whenever the plane “overnighted.” The researchers took their samples from such surfaces.
Misdirecting the blame
The study comes with plenty of caveats. All the observed flights were with the same airline, involved only single-aisle aircraft and flew coast-to-coast. Furthermore, half of the passengers never left their seats.
“On short-hop flights, the amount of movement may be less,” Hertzberg and her colleagues point out. “Conversely, on longer international flights, there will be substantially more movement of passengers and crew, leading to many additional close contacts.”
Still, the results may be a bit reassuring to some frequent flyers — at least about picking up an unwanted illness while actually in an airplane.
“I hear people say, ‘Oh I get so sick on airplanes.’ But I wonder how much of that is recall bias,” Hertzberg told Everyday Health reporter Shari Roan. “People tend to focus on airplanes. You don’t recall you were also standing on the subway platform or in line at the hotel or in the boarding area, ready to board. There are lots of places along the path of taking a trip from point A to point B that might allow for transmission.”
“We strongly feel if you are observing good hygiene — hand washing, using hand sanitizer and keeping your hands away from your face — that should be pretty good protection,” she adds.
FMI: You can read the study on the PNAS website. The study was funded by Boeing, although the researchers say the company had no say over its design or findings.