IATA, Aircraft Manufacturers Provide Proof Of Low Inflight Virus Transmission Risk
People are at far higher risk of being struck by lightning than of catching the novel coronavirus during a flight on a commercial airliner, the latest numbers on onboard transmissions seem to show.
Briefing media Oct. 8, IATA medical advisor David Powell said about 44 people are thought to have caught the virus during a flight. That is among the 1.2 billion people who have flown so far this year, making the risk of transmission about one in 27.3 million. Even if some 90% of cases were not reported and the risk were 10 times higher, it would mean the likelihood of catching the virus that causes COVID-19 on a flight would be one in 2.73 million, making it “an uncommon event,” Powell said.
He compared it to the probability of being struck by lightning, which he believed was between one in 500,000 and one in 1.2 million, making it a far higher risk.
Until a COVID-19 vaccine becomes available and virus testing is widely available, affordable and rapid, the air transport industry is struggling to convince people that it is safe to fly, although some progress appears to have been made in communicating the multi-layers of measures that are in place and why they work. Powell said that in a recent survey of people who had flown, 86% said they felt safe. But 60% said they felt cabin air was dangerous and the biggest single fear was of catching the virus from a passenger sitting next to them. The other challenge is convincing all those people who are not flying that it is safe to do so; IATA August travel data showed that passenger numbers worldwide were still down by 75% compared with a year ago.
Of the 44 known inflight transmission cases, most occurred early in the year before masks were widely worn. Most airlines now mandate masks for passengers and crews. Most of the cases involved just one or two transmission on a flight. There were two exceptions, both happening in March: a London-Hanoi flight in which 15 cases were confirmed and a Sydney-Perth flight in which there were 11 cases. On the London-Hanoi flight, 12 of the infected passengers were in business class, two were in the economy cabin and one cabin crewmember was affected, Powell said.
In the same briefing, representatives of Airbus, Boeing and Embraer shared information on extensive research they have conducted independently to understand the effectiveness of onboard protections such as the cabin HEPA air filter system, top-to-bottom air flows, the natural barriers formed by seatbacks, and mask wearing. All have conducted 3D computational fluid dynamic models that have provided insight into what happens to cough droplets in a cabin. The downward flow of air that comes from the cabin ceiling and is completely refreshed every two to three minutes pushes larger droplets to the floor and washes them out. Smaller aerosol droplets, which can reach further, are also massively dissipated by the air system.
Bruno Fargeon, leader of Airbus Engineering’s Airbus Keep Trust in Air Travel initiative, said models show a single cough by one passenger could create some 10,000 such droplets, but a maximum of just five droplets might reach a passenger seated next to the cougher. The same models also looked at what happens when a person coughs on the ground but is socially distanced by 1.8 m (6 ft.) from other people. Models found the likely maximum number of droplets that might reach a person 1.8 m away was 10.
“So being on an aircraft is safer than being six feet away on the ground,” Powell said. The biggest difference is the effect cabin air and filters have on droplets.
Dan Freeman, engineering director at Boeing’s Confident Travel Initiative, said the company had done “vast amounts of research” and modeling and live testing on narrowbodies and widebodies, taking worst-case scenarios with masked and unmasked passengers. Even in worst-case scenarios, the research indicates that being on an aircraft is equivalent to being 7 ft. or more away from other people in an indoor ground environment, he said. Boeing models were done based on full aircraft with every seat occupied.
Luis Carlos Affonso, Embraer SVP engineering, technology and strategy, noted that their modeling based on seven rows of seating did show that mask-wearing further reduced the risk of droplets being dispersed, with the risk being six times higher if masks are not worn.
“Masks should be worn,” Fargeon agreed.
“We are not saying there is no risk; it’s about relative risk to all the other things people do and it’s important for people to understand that risk in air travel is very low,” Freeman said.