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A travel group report says flying is safe. The doctor whose research it cited says not so fast.

An airline group reported a “low incidence of inflight COVID-19 transmission," but some experts say there’s more to the research.


(Woody Harrington for The Washington Post)

The International Air Transport Association (IATA), a global airline trade group representing 290 carriers in 120 countries, published a report this month aiming to reassure grounded travelers about the future of flying. The group collected medical journal data on in-flight coronavirus cases and used it to declare that commercial flights have a “low incidence of inflight COVID-19 transmission” when masks are worn.

Following an abundance of new research, the report says, only 44 cases of coronavirus have been linked to a flight, during a period when 1.2 billion passengers traveled.

But a doctor whose work was cited in the report says that the group is misrepresenting his findings by only counting proven flight-linked cases that were published in medical journals.

“IATA is taking it to an extreme saying there’s ‘little’ risk in flying,” says David Freedman, an infectious-disease specialist at the University of Alabama whose study is cited in the IATA report. “What they want is to throw this number on the risk of flying … and we don’t know what that risk is yet. I’m not saying the risk is high, but there is some risk. It just looks like masks help a lot.”

The bottom line, Freedman says, is that cases linked to air travel are very difficult to scientifically prove because passengers are not usually monitored after flying and therefore are not tallied if they become sick. It’s also nearly impossible to determine whether sick passengers picked up the virus on a plane as opposed to in an airport or on the way there, he says. “And if you can’t prove it, it doesn’t end up in a journal."

Freedman’s cited study, published in September 2020, says that “the absence of large numbers of published in-flight transmissions of SARS-CoV-2 is not definitive evidence of safety.”

While an abundance of in-flight research on covid-19 has recently come to light, Freedman is not alone in his assessment that it’s unclear if flying is a low-risk endeavor amid the pandemic.

Brad Pollock, the associate dean of public health sciences at the University of California at Davis, agrees with Freedman’s assessment of IATA’s report, calling it an “overreach.” Studies do not account for unpredictable passengers who board planes every day, he says.

“There’s movement in the cabin to consider, but also so many people improperly wear a mask below their nostrils,” Pollock says. “That’s more of an issue than what kind of mask they’re wearing. If everyone wears their mask properly on the plane, we’re going to be much better off.”

In September, the Centers for Disease Control and Prevention estimated that nearly 11,000 people have been potentially exposed to the coronavirus on flights. The CDC told The Washington Post that of those in-flight exposures, “an absence of cases identified or reported is not evidence that there were no cases.” On Monday, it updated its guidance to “strongly recommend” all passengers and crew members wear masks.

When asked for comment, IATA spokesperson Perry Flint told The Post over email: “It is possible that the actual number of transmissions is greater than the 44 cases we have been able to identify. And if we were able to determine how many passengers have flown internationally while infectious, this would be tremendously useful. However, these numbers are not available.”

Flint also maintains that “it is true that the documented, published transmissions in flight are very low, and those that have occurred with onboard mask wearing are lower still — and it is true that well over a billion people have travelled by air during the pandemic.”

Experts say there is reason to be optimistic about the efficacy of in-flight air-filtration systems, especially when they are paired with mask-wearing. However, there are more factors at hand than just airflow and case counts — with the most important one being whether airlines enforce rules and whether passengers follow them.

A study released this month by the Department of Defense that simulated in-flight transmission of virus droplets suggests that passengers would need to be near an infectious person on a plane for 54 hours to receive a significant dose of the virus. The study credits high-efficiency particulate air (HEPA) filters.

But the study, which the Pentagon partnered with United Airlines for, has not been peer reviewed. And it was conducted in aircrafts with more stable conditions than those seen in a typical commercial flight.

The DOD study “assumes ideal conditions with masks on 24/7 and no movement in the cabin while in flight,” says Sara Nelson, international president of the Association of Flight Attendants-CWA, a union of 50,000 flight attendants across 17 airlines. While the findings are encouraging, Nelson says, airlines and regulators should not take them as a signal to change any existing health protocols.

“To approach the levels of safety suggested by this research, regulators need to require effective masks be worn properly by every occupant, onboard service must be minimized, ventilation must be maximized, HEPA filters must be required and replaced often, and interiors must be cleaned, sanitized and disinfected regularly,” Nelson says. “Masks are essential on planes.”

The Flight Safety Foundation, an international aviation nonprofit, endorsed the Department of Defense’s study and IATA’s finding, saying “it’s safe to fly” as long as airlines continue to utilize masks, enhanced cleanings, and socially distant boarding and deplaning procedures. The foundation stops short of putting a risk or infection rate on airplane cabins, but it says that global testing should be enhanced and can empower governments to lift “haphazard” travel restrictions.

“There is a growing body of evidence that shows aircraft and airports have very low levels of transmission and the risk of contracting the virus during the air travel journey appears extraordinarily low,” said Hassan Shahidi, the Flight Safety Foundation’s president. “We do not have an infection rate, but we’re monitoring cases to see if one can become available.” The group is collecting data from Hawaii’s testing-based entry program for travelers, in hopes of creating more data about the risk of in-flight transmission, a program that is in its early stages.

The latest findings on how effective masks are in flight are from a study Freedman conducted of flights operated by Emirates, which has a strict mask policy that requires face coverings throughout the entire journey, from the airport up to deplaning. On one Emirates flight, 27 coronavirus-positive individuals flew with masks on, Freedman says. They appeared to cause only two in-flight transmissions.

In those rare scenarios where masking is rigid, Freedman says, “the risk is low but it’s more than zero … and if you’re in the wrong place — say next to an infected person eating chips for an hour — there is not much you can do about it.”

Read more:

Southwest will start filling middle seats on flights beginning Dec. 1

CDC to passengers and workers: Wear a mask when you are on a plane, train, bus or other public transit

How much does a hotel’s ventilation system matter right now? We asked the experts.

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