Unless, that is, you’re directly next to an infected person, or a steward is contagious

Flyers who live in fear of catching bugs on every flight, take heart: the risk of picking up respiratory infections while cruising at 35,000 feet may be slimmer than you think.



Scientists used a computer model to crunch information on how people moved around aircraft on flights lasting three-and-a-half to five hours. They found that passengers sitting one row in front, or one row behind, a person with flu had an 80% risk of catching the bug.



The same level of risk applied to those sitting one or two seats either side of the infectious traveller, but for all other passengers, the risk was less than 3%. An infected cabin crew member infected 4.6 passengers per flight, the model found.



“What we showed is that outside this perimeter there is very little probability of becoming infected on an airplane,” said Vicki Hertzberg, a professor of biostatistics and director of the Center for Nursing Data Science at Emory University in Atlanta. “You don’t have to worry about the coughing coming from the person five rows behind you.”



Health officials have recorded more than a dozen cases of bugs being spread on planes, ranging from instances of pandemic influenza to severe acute respiratory syndrome, or Sars. But despite the potential for passengers to fall ill, little has been known about the health risks that sickly flyers pose.

To find out more, researchers working with Hertzberg and Boeing in Seattle boarded 10 domestic US flights and took notes on how passengers and crew moved around the aircraft. The flights left Atlanta for San Diego, Los Angeles, San Francisco, Seattle or Portland, and all of the planes had two rows of three seats separated by a central aisle.

In total, the movements of 1,540 passengers and 41 cabin crew were plugged into the computer model, which assumed that flu-ridden passengers infected others at the rate of 0.018 per minute of contact. The infection rate, according to a report in Proceedings of the National Academy of Sciences, was chosen to produce something close to a worst-case scenario.

Hertzberg said the computer only modelled the risk from viruses spread by droplets sprayed out in coughs and sneezes, and did not take into account the potential for viruses to float around in the cabin’s air. Steven Riley, professor of infectious disease dynamics at Imperial College London, said that while the risk of picking up flu on any one flight was low, larger studies with enough passengers to reveal real infection rates were needed.

Asked if she had tips for flyers who find themselves next to a spluttering passenger, Hertzberg said people should wash their hands well and not touch their faces, because viruses can be picked up through the eyes, nose and mouth. As for requesting another seat, good luck with that. “Flights are so full these days, there would probably be no place to move to,” she said.

