The message from Canadian transport minister Marc Garneau was clear: there is “no evidence” anyone has ever contracted the novel coronavirus on a commercial airliner.
The odds of catching the virus on a commercial flight are “infinitesimally small,” he added, citing current safety measures, such as wearing masks, pre-screening of passengers and air filtration systems onboard planes, as key reasons why.
Garneau made the comments during a televised interview that aired in July.
“The (data) does not indicate transmission onboard aircraft,” Garneau told CBC in the interview. “And that’s important as scientific evidence.”
Garneau’s department, Transport Canada, regulates the airline industry, which is asking the government to reduce some travel-related coronavirus restrictions.
While the minister downplayed concerns about catching COVID-19 on a plane, at least two infectious disease experts told Global News the risks are enough that they won’t be getting on a plane for non-essential travel anytime soon.
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Researchers have also published several reports, including a research letter published in August, another letter published in April, plus a report cited by Garneau’s office, that document cases where passengers were likely infected with the novel coronavirus on flights. The research suggests there are low risks of COVID-19 transmission on planes.
“I’m not planning on flying for my summer vacation,” said Dr. Allison McGeer, an infectious disease physician and member of a government expert panel on COVID-19..
“If I’m not flying because I don’t need to, then that just makes flying safer because fewer of us are doing it.”
Meanwhile, Dr. Craig Jenne, an infectious disease specialist at the University of Calgary, said he isn’t taking any unnecessary trips right now.
Jenne believes the risks associated with flying are low, but he wouldn’t describe them as “infinitesimally small.” He also said there are many factors associated with air travel that increase the possibility of contracting COVID-19.
It’s “impossible or very difficult” to pinpoint exactly when someone is infected with a virus while travelling, he added. It could happen on the way to the airport, going through security, on the plane itself or anywhere in between, he said.
This makes it difficult for public health officials to say with absolute certainty whether a traveller contracted COVID-19 on a plane or elsewhere.
“Although the risk is low, it is still a higher risk than not travelling,” Jenne said.
Limitations of scientific research
At the time Garneau made his remarks about the safety of flying in mid-July, the volume of air travellers in Canada was on the rise and confirmed cases of COVID-19 globally were continuing to soar.
As of July 1, Canada’s two largest airlines, Air Canada and WestJet, both announced they would resume booking the middle seats on flights, after most airlines had temporarily blocked selling them for months.
When pressed on whether his comments minimized the risk of flying, a spokesperson from Garneau’s office said, “it is not Transport Canada’s position or assertion that there is ‘zero risk’ of COVID-19 transmission aboard aircraft.”
His office also said it is aware of reports of possible transmission on commercial aircraft, but said these reports were completed before the current “multi-layer” strategy, meant to reduce the risks of contracting COVID-19 during air travel, was implemented.
Jenne, meanwhile, said Transport Canada is relying on dated research that does not necessarily reflect changes to the number of people travelling, plus increased safety measures imposed by airlines and governments, such as requirements to wear masks.
“Although the evidence for frequent or easy transmission on airplanes is lacking, or at least we’re still learning about the process, we have to consider it in the bigger picture,” Jenne said.
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Transport Canada points to a February letter published by a group of physicians in the Canadian Medical Association Journal to bolster its claims that flying is safe.
The letter concluded there was no evidence of COVID-19 transmission on a flight carrying the first known people with COVID-19 in Canada from Guanghzhou, China to Toronto in January.
But Dr. Kevin Schwartz, an infectious disease specialist with Public Health Ontario who authored the letter, has since told Global News that the report was “by no means a comprehensive study” on the safety of air travel and that most passengers on the plane were not actively monitored or tested for the novel coronavirus.
According to the letter, one passenger sitting near the infected travellers developed symptoms of COVID-19, as did five other passengers sitting further away. All six tested negative for the novel coronavirus.
“There is no scenario where there is no risk,” Schwartz said. “There is always going to be a risk in these scenarios and there is going to be a risk on an airplane.”
Testing protocols in January also did not target potentially infected people without symptoms, Schwartz said, but he still believes the report’s findings are sound and said it’s unlikely any passengers on the flight contracted COVID-19 based on the evidence.
He also said new safety measures, such as requiring masks and pre-screening of passengers, significantly lower the risks.
Possible transmission onboard aircraft
Scientists have found cases of possible transmission on a plane in their reviews of at least three flights.
One was in late January between Singapore and Hangzhou, China. Researchers published their findings in the journal Travel Medicine and Infectious Disease, which identified one passenger who developed the virus after sitting near four infected passengers for an hour.
The researchers said the passenger had no known previous exposure to the virus, and was likely infected on board the Jan 24 flight after not wearing his facemask correctly.
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A second research letter, written by French virologists, reported likely transmission of the virus on a flight from the Central African Republic to Paris in late February.
The report, published by Travel Medicine and Infectious Disease on April 1, concluded that a passenger with no known exposures to COVID-19 before or after the flight was most likely infected on the plane by another passenger who was confirmed positive. Passengers on the flight were not wearing masks, researchers said.
“This report illustrates how easily SARS-CoV-2 may travel together with their human carriers and spread the virus on board (a plane),” researchers wrote.
“Travel restrictions clearly make sense in the current context, not only to limit the spread of the disease to still unaffected areas but also to prevent travelers from getting infected on board.”
A third research letter published by the American Medical Association on Aug. 18 documented two more cases of COVID-19 likely transmitted on a flight from Tel Aviv to Frankfurt in early-March, before masks were made mandatory on planes.
When first contacted by Global News, Garneau’s spokesperson Livia-Marina Belcea downplayed the early research, noting that no one has confirmed the transmission of COVID-19 on any flights in Canada.
“To date, Transport Canada is not aware of any cases of passenger-to-passenger transmission of COVID-19 on a flight to, from, or within Canada,” said Belcea.
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Belcea said Transport Canada is in regular contact with the Public Health Agency of Canada, which is monitoring for reports of verified passenger-to-passenger transmission. As of Aug. 14 there had been no such reports, she said.
“The global consensus is that the risk (of transmission onboard flights) appears to be low. Everyone remains cautious and vigilant,” Belcea said.
“Transport Canada acknowledges that the understanding of COVID-19 is evolving rapidly, and remains prepared to adapt its approach based on the best available evidence.”
Garneau also noted in the July interview that his department is collecting data about passenger-to-passenger transmission of COVID-19 on flights.
Garneau’s office referred questions about this information to the Public Health Agency of Canada, which said it could not release the data because of privacy concerns.
Lack of ‘superspreader’ events on planes
When asked to compare the spread of the novel coronavirus to the first SARS virus in the early 2000s, Jenne said that the two viruses appear to behave very differently and that direct inferences should not be made.
A study published in the New England Journal of Medicine in 2003 documented a “superspreader” event of the original SARS virus aboard a flight from Hong Kong to Beijing. Researchers reported a single SARS-infected traveller transmitted the virus to 22 of 120 passengers and crew on board the flight.
Although scientists have documented some COVID-19 superspreader events since the beginning of the pandemic, they haven’t identified any such case on an airplane, despite tens of thousands of commercial flights over the past few months.
”The fact that we haven’t (seen this) is one of those red flags that says: OK, is it actually spreading on a plane?” Jenne said.
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Caroline Colijn, an applied mathematician from Simon Fraser University who is also a member of the federal Chief Science Advisor’s expert panel on COVID-19, said flying is relatively safe compared to other activities because passengers are mostly inactive during flight and don’t engage in risky activities, such as shouting, dining and socializing face-to-face.
She also said the two-meter physical distancing requirement isn’t necessarily needed on planes because masks are mandated.
Meanwhile, a study from MIT researchers based on computer modelling of data collected in the U.S. found that while filling the middle seat on planes increased the risk of transmission significantly, the odds of contracting COVID-19 during a flight were still just 4,300 to one compared to 7,700 to one when the middle seat was empty.
Because this research was conducted in the U.S., it does not account for lower overall infection rates in Canada.
Airlines call for less restrictions
Canadian airlines have been calling on the government to loosen travel restrictions for months.
Mike McNaney, president of the National Airlines Council of Canada, said airlines are following all government requirements and taking additional measures to keep passengers safe, including those related to border restrictions and pre-boarding health checks. He also said airlines have enhanced sanitization onboard planes.
McNaney said air travel is safe for several reasons, including: mandatory masks, pre-screening of passengers, increased sanitization and high-efficiency particulate air (HEPA) filters onboard planes, which capture up to 99.9 per cent of all large particles, including bacteria and viruses.
Airlines have also introduced no contact check-in and other safety measures at airports meant to reduce the likelihood of transmission before and after getting on a plane, he said.
“The provisions that are in effect from the federal government do not ban travel,” he said. “The airports and the airlines are undertaking all the appropriate measures from a public health and safety perspective.”
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McNaney said the airline industry is experiencing significant financial pain as a result of COVID-19, with tens of thousands of employees laid off and billions of dollars in lost revenue. At present, he said, Canadian airlines are operating at roughly 15 per cent of normal capacity, which cannot be maintained indefinitely.
“We do have to start a targeted risk based approach to restarting aviation,” he said.
This would involve moving away from the current “blanket” ban on non-essential international travel toward opening up the border to visitors from countries deemed safe, McNaney said, where the virus is under control and where protocols exist for measuring and tracking any potential outbreaks.
“The industry in Canada is still at stage zero in the recovery process,” he said.
McNaney also said other countries, such as European Union members, have begun reopening travel and loosening restrictions based on recommendations made in a report published by the International Civil Aviation Organization in May.
“We believe the time is appropriate here in Canada for the federal government to also look at that very targeted, specific approach,” he said.
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At present, the government recommends avoiding all non-essential travel outside Canada. There are, however, no rules on where Canadians can fly and for what purposes.
The government says it’s up to individuals to determine what non-essential travel is “based on family or business requirements, knowledge of a country or region, and other factors.”
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But infectious disease physicians are still warning against unnecessary air travel, especially to hotbeds for the novel coronavirus, such as the United States, where community spread is common. They also say that while the risk of flying may be low, it’s not zero.
McGeer, for example, said she’s avoiding all non-essential travel partly because she’s at higher risk of contracting COVID-19 due to her age and partly because she thinks if everyone returns to pre-pandemic behaviours then the number of infectious will increase substantially.
“If we go back to our lives as they were in February, we’re going to be in trouble,” she said.
Schwartz, meanwhile, said he believes the risks of flying within Canada are low enough that people could start some non-essential travel so long as they adhere to current public health advice and don’t engage in risky activities once they arrive at their destination.
However, when it comes to places with high levels of community spread, such as some parts of the U.S., he said travellers should still remain cautious.
“I’m not planning any trips in the near future to the United States,” he said.
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