A Massachusetts Institute of Technology analysis tries to quantify the risk of catching COVID-19 from flying.
If you decide to fly, the odds that you will pick up COVID-19 are low, according to one expert analysis. Despite the known dangers of crowded, enclosed spaces, planes have not been the sites of so-called super-spreading events, at least so far, says a Bloomberg Opinion. That’s not to say flying is perfectly safe – safety is relative and subjective. But as restrictions continue to change, the only way to move forward through this long pandemic is to start thinking in terms of risk-benefit ratios. Very little is without risk, but perhaps some risks – such as flying – are small enough to warrant taking.
Arnold Barnett, a professor of management science at the Massachusetts Institute of Technology, has been trying to quantify the odds of catching COVID-19 from flying. He’s factored in a bunch of variables, including the odds of being seated near someone in the infectious stage of the disease, and the odds that the protection of masks (now required on most flights) will fail. He’s accounted for the way air is constantly renewed in airplane cabins, which experts say makes it very unlikely you’ll contract the disease from people who aren’t in your immediate vicinity – your row, or, to a lesser extent, the person across the aisle, the people ahead of you or the people behind you.
What Barnett came up with was that we have about a 1/4300 chance of getting COVID-19 on a full 2-hour flight – that is, about 1 in 4300 passengers will pick up the virus, on average. The odds of getting the virus are about half that, 1/7700, if airlines leave the middle seat empty. He’s posted his results as a not-yet-peer-reviewed pre-print. The odds of dying of a case contracted in flight, he found, are even lower – between 1 in 400,000 and 1 in 600,000 – depending on your age and other risk factors. To put that in perspective, those odds are comparable to the average risk of getting a fatal case in a typical two hours on the ground.
The numbers all sound low enough, though Barnett says they are still high compared to the 1 in 34m odds your flight will end in a deadly crash. He told me he wouldn’t fly right now because his age, 72, puts him at higher risk than the average American, and he says you have to consider the risk of adding to the problem by getting the virus and unknowingly passing it on to others.
Other experts have been mixed on whether they, personally, would fly. The report says 15 epidemiologists and infectious disease experts surveyed, 13 said they would not fly at this time – however it wasn’t clear whether they had any reason to get on a plane.
University of Massachusetts biology professor Erin Bromage says he is flying every week, as he advises federal, state and district courts on how to reopen while minimising risks. Whereas many experts are taking a zero-tolerance for risk approach, he’s trying to find a middle ground – and helping others do it in a rational way.
Drawing on a background in industrial mechanics and pilot training (an injury forced him to switch career paths into biology), Bromage says that the air exchange system in planes is better than in hospitals, with the air in the cabin being completely replaced 30 times every hour. He agrees with MIT’s Barnett, though, that it’s possible to transmit the disease to or from your close neighbours.
He and Barnett both suggested that customers should, if possible, choose an airline, such as Jet Blue, that promises to keep the middle seat open. That cuts way back on the odds of getting or giving the virus. JetBlue also promises that solo travellers won’t have a neighbour in a two-seat row.
The report says real-world data bodes well for flying, too. Australia has been using contact tracing to investigate COVID transmission on hundreds of flights, and has found that while infected people got on planes, nobody got infected on a plane. Worldwide, there have been a couple of individual transmissions possibly linked to flights, but no super-spreading-type events.
Assuming we’ll be living with this disease for months to come, we will need ways to separate low-risk activities from high-risk ones. Keeping informed of relative risks can help us do that. By worrying less about the relatively safer part of a trip – the actual flight – we can pay more attention to the potentially riskier parts, such as crowds and tightly packed lines at the airport.
Of course, we’re all obligated to avoid adding to the spread of the disease, and this means taking precautions in the air, such as wearing a mask and staying home if sick, and keeping a distance from others at the airport.
What happens at your destination matters too. Traveling around and mingling with distant contacts can increase the risk of spreading the virus more than mingling with a comparable number of people closer to home. So, people can help themselves and others by driving their own cars to the airport and renting cars wherever they arrive, rather than taking taxis or ride-shares.
In the old normal, Bromage would wrap up his advisory duties and have dinner with the people he’s working with. Now, he just goes back to his hotel room. “It’s quite lonely,” he says. Like so much this year, it’s a compromise.
Abstract
We use recent data and research results to approximate the probability that an air traveler in coach will contract Covid-19 on a US domestic flight two hours long, both when all coach seats are full and when all but middle seats are full. The point estimates we reach based on data from late June 2020 are 1 in 4,300 for full flights and 1 in 7,700 when middle seats are kept empty. These estimates are subject to both quantifiable and non-quantifiable sources of uncertainty, and sustain known margins of error of a factor about 2.5. However, because uncertainties in key parameters affect both risk estimates the same way, they leave the relative risk ratio for fill all seats compared to middle seat open close to 1.8 (i.e., close to 1/4,300)/(1/7,700). We estimate the mortality risks caused by Covid-19 infections contracted on airplanes, taking into account that infected passengers can in turn infect others. The point estimates, which use 2019 data about the percentage of seats actually occupied on US flights, range from one death per 400,000 passengers to one death per 600,000. These death-risk levels are considerably higher than those associated with plane crashes but comparable to those arising from two hours of everyday activities during the pandemic.
Author
Arnold Barnett
[link url="https://www.bloomberg.com/opinion/articles/2020-08-05/is-it-safe-to-fly-here-are-the-odds-of-catching-covid-on-a-plane?utm_campaign=KHN%3A%20Daily%20Health%20Policy%20Report&utm_medium=email&_hsmi=92753199&_hsenc=p2ANqtz–gt4RcEbV6vrFi3Jbna0sx3HAtBX_wBvdulKDAP-C9GYh27XpovD03AGOqRFZnxgS8SUjz4cMQIZhk0h8L_9tze2R4cA&utm_content=92753199&utm_source=hs_email"]Full Bloomberg Opinion[/link]
[link url="https://www.medrxiv.org/content/10.1101/2020.07.02.20143826v3"]medRxiv abstract[/link]