Experts concerned about increased risk of COVID-19 transmission on flights

Open this photo in gallery:

At least two flights every day into or within Canada carried a passenger with a confirmed case of COVID-19 over the course of a week in June, according to federal data, raising concerns about the increased risk of transmission as more people start to travel.

From June 17 to 23, at least eight domestic flights and five international flights into the country had a person with COVID-19 on board, according to the federal government. On Wednesday, the Nova Scotia Health Authority issued a warning about an additional flight with a potential exposure to COVID-19, a WestJet flight from Toronto to Halifax on June 26.

Most of the domestic flights originated in Toronto, along with two from Vancouver and one from Winnipeg. Some of the international flights arrived in Vancouver, Toronto and Montreal from places such as Los Angeles, New Delhi and Port-au-Prince, while others connected through Canada on to other destinations.

It’s unclear how many domestic flights and international arrivals there are each day. The Calgary Airport Authority said between June 17 and July 1, there were 607 domestic flight arrivals and 36 U.S. flight arrivals there. The Toronto Pearson Airport website listed more than 100 domestic and international arrivals scheduled for Thursday.

Infectious disease experts say they’re concerned about the possible risks of COVID-19 and travel, particularly as more countries loosen their restrictions and airlines introduce more flights. As of July 1, for instance, Canadians are now allowed to fly into the European Union and airlines such as Air Canada are boosting the number of flights they offer to countries there. Air Canada and WestJet also eliminated physical distancing on planes this week.

Janine McCready, an infectious diseases physician at Toronto’s Michael Garron Hospital, said increased amounts of travel combined with the elimination of physical distancing on board is “an infectious disease doctor’s worst nightmare at this point.”

Dr. McCready said she’s particularly concerned about increased travel to destinations within the United States, which is experiencing surging levels of COVID-19 in most states.

Isaac Bogoch, an infectious diseases physician at Toronto General Hospital, said he’s more concerned about the possibility of COVID-19 transmission when people arrive at their travel destination, rather than the risks of air travel itself.

Dr. Bogoch said there are few cases of COVID-19 transmission on airplanes and that it doesn’t pose a significant risk, especially with rules in place to prevent transmission, such as requiring passengers to wear masks. He added that the way air is circulated on planes may help reduce transmission risk.

“I think that while the risk [of transmission on airplanes] is not 0 per cent, it’s probably lower than what people think it is,” Dr. Bogoch said.

He added that as long as COVID-19 is circulating without a vaccine, there will be some chance of transmission of the coronavirus in public places, such as airplanes.

“There’s no zero-risk scenario,” he said. “If people are choosing to travel, they are potentially going to be exposed.”

For instance, an article published in the Canadian Medical Association Journal in February documented that there were no cases of COVID-19 transmission on a flight from China to Toronto in January. A man on that flight was experiencing symptoms of the disease and public-health officials conducted contact tracing on people sitting within close proximity to him. None of them developed COVID-19.

In a statement, a spokesperson for WestJet said the company decided to remove its physical distancing policy, under which certain seats on airline cabins were blocked off, because there are other measures in place to reduce COVID-19 transmission. For instance, the airline uses hospital-grade air filters and has implemented a new rigorous cleaning process, the spokesperson wrote.

A spokesperson for Air Canada said in a statement the airline also uses a hospital-grade air filtration system, which ensures air is regularly refreshed to help prevent transmission. The airline will also alert customers in economy class if their booked flights are near capacity and give them the option to change flights at no additional cost.

Under the current federal rules, passengers arriving into Canada are required to undergo a 14-day quarantine period.

Dr. Bogoch said that passengers travelling within Canada could potentially pose a greater transmission risk, as many provinces have no quarantine requirements and people are more likely to interact with others when they travel.

“Human mobility drives the transmission of this infection,” Dr. Bogoch said. “We can bring infections from one part of the country to another unknowingly. This can trigger small outbreaks. We have to be prepared for that scenario.”

In an e-mail, a spokesperson for Transport Canada said it has introduced several new rules to protect airline passengers during travel, including mandatory health checks, universal masking policies and temperature checks of all passengers from international flights. The spokesperson also wrote that Transport Canada “encourages air operators to keep an additional space between passengers when seats are available and when safe to do so.”

Our Morning Update and Evening Update newsletters are written by Globe editors, giving you a concise summary of the day’s most important headlines. Sign up today.