Coronavirus FAQ: So Do Lots Of People Get COVID-19 From Flying?

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A flight attendant adjusts protective glasses. There has been little documentation about COVID-19 transmission on planes. / Reuters

Each week, we answer "frequently asked questions" about life during the coronavirus crisis. If you have a question you'd like us to consider for a future post, email us at goatsandsoda@npr.org with the subject line: "Weekly Coronavirus Questions."

Air travel has seldom looked the way it does right now.

International aviation is operating just 2% to 4% of its normal number of flights.

And plane tickets are selling for dirt-cheap — like a famed $6 ride from Newark, N.J., to Fort Myers, Fla., earlier this year.

The economics of aviation has certainly changed.

So has the nature of air travel. A new spate of rules and techniques — from mask requirements (now enacted by all major airlines) to symptom-screens for signs of the novel coronavirus — has emerged quickly. Airlines are attempting to reassure disease-fearing potential passengers, who may be understandably nervous at the idea of being trapped indoors in close proximity to many people for hours on end.

And there's reason to be nervous. A new study published this week discovered two likely transmissions of COVID-19 on a four-hour-plus flight from Tel Aviv, Israel, to Frankfurt, Germany, carrying 102 passengers. The study followed a 24-member tourist group, who, seven days earlier, had contact with a hotel manager who was later diagnosed with COVID-19. Seven of those tourists tested positive for the virus upon arriving in Frankfurt — as did two passengers who were seated within two rows of one of the tourists.

Which brings us to our frequently asked questions for the week. How risky is air travel during a pandemic? And if it is risky, why aren't we hearing about more cases where passengers were infected on a flight?

Or to put it another way: Could the headline of one CNN article, published on Thursday, be right: "The odds of catching Covid-19 on an airplane are slimmer than you think, scientists say."

The truth is, there are no easy answers.

One report in early August by the International Air Travel Association Medical Advisory Group explained that "relatively little research has been published on in-flight transmission of COVID-19."

That's because it's tricky for health authorities to determine what COVID-19 transmission looks like on planes. It's logistically complicated. And there's no clear method for doing so.

Abraar Karan, a Harvard Medical School physician, says tracking flight transmission is challenging since it requires coordination between health departments in multiple states or countries — as well as credible knowledge that a patient was infected on the flight specifically (as opposed to before or immediately afterward.) So while it might be possible to trace a local case of the virus in a small town to one individual, it's much harder to do the same for flights.

That said, there are numbers and case studies available — and those findings do seem to paint a reassuring picture for flying. Specialists in air travel and disease agree with this reassuring, albeit preliminary, perspective.

That's the view of Lin Chen, an infectious disease doctor and president of the International Society of Travel Medicine and director of the Harvard-affiliated Mount Auburn Hospital Travel Medicine Center. She says a review of the available data, though varied, shows that the overall rate of infection from air travel is "very, very low."

She points to one January flight from China to Canada, when a passenger with a symptomatic case of COVID-19 did not infect any of the 350 passengers on board, according to a brief report by Canadian researchers. And on a flight from New York to Taipei, Taiwan, a passenger with COVID-19 also did not infect anyone else on board, according to Chen.

Researchers have theories for why that's the case, but again, Chen emphasizes we don't really know for sure. Maybe it's masks and symptom-checking. Or the deliberate underbooking many airlines are doing to restore confidence in flying. Or the really insanely efficient ventilation systems.

"Planes have good ventilation systems [in the form of] HEPA filters, with 15 [to] 20 [air] changes per hour, far more than most workplaces," Karan says. An "air change" means air in the cabin is sucked out and replaced with filtered and/or new air.

Then again, there are caveats that complicate the data picture.

"Testing may have been suboptimal in January [to] March, and we may have missed some cases that were acquired in-flight," Chen says.

Or perhaps the low numbers just reflect low air traffic, which has been stunted by the virus. Karan explains that the overall number of passengers has been relatively low compared with usual levels, so it's possible the chance of transmission is lower just by "sheer numbers." When he took a flight last month, he didn't see a single person in the security line.

If passenger volume swells and airlines add back flights, Chen says we may expect to see more cases as more exposures occur and especially as access to testing improves.

Then again, Chen stresses that the changing behaviors of travelers and airlines could keep numbers down.

"Travelers may be more careful now, and precautions have been updated, so travelers may take more precautions now compared to the January-March period," she says.

In other words, she says: "It's hard to predict" what will happen vis-a-vis COVID-19 transmission on flights in the months ahead.

Beyond this there is also a broader consideration to make: Regardless of the in-flight risk of getting infected yourself, some reports, such as this one in Time, have pointed out that just by moving people from one location to another, air travel is likely contributing to the spread of the virus.

For that reason, experts stress that if you do travel, you should be disciplined about taking adequate precautions before and while flying — wearing masks, hand washing, maintaining social distance and avoiding high-touch points, among other standard-issue pandemic rules.

And keep in mind that long road trips also carry risks. You can read more about deciding to travel in an earlier FAQ.

In any case, as health experts continue to process information and roll out new rules for air travel, one thing is clear: People want to fly. So much so, in fact, that some enterprising excursionists have begun to take virtual-reality flights ... to nowhere. Though at $62, the First Airlines voyage, featuring a full-flight simulation (including safety precautions and a four-course meal) might not cost you as much as a bona fide, pandemic-priced first-class ticket.

Pranav Baskar is a freelance journalist and U.S. national born in Mumbai.

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