BCCDC data shows significant decrease in COVID-19 exposures on flights in September

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September saw a dramatic decrease in the number of COVID-19 cases detected aboard flights involving B.C. airports compared to August, but was still one of the busiest months of the pandemic for flight exposures.

As of Oct. 6, 251 flights that took off from or landed at B.C. airports during the month of September had been added to the B.C. Centre for Disease Control's list of exposures.

That total is the third-highest number of flight exposures during a single month since the pandemic began, and it may grow to eclipse the 261 flights recorded in April of this year as more people test positive and the BCCDC becomes aware of their recent travel.

September almost certainly won't catch August, however. That month ultimately saw 522 flights added to the list, exactly doubling April's previous record. 

It's unclear what exactly caused the August surge, though it coincided with rapid growth in B.C.'s daily COVID-19 caseload.

At the beginning of August, the province's seven-day rolling average for new daily infections was 176. By the end of the month, it had risen to 685.

September, by comparison, had a higher - but more stable - rolling average. It was 698 on Sept. 1 and 742 on Sept. 30, and it never got higher than 800 or lower than 600 over the course of the month.

The BCCDC has previously told CTV News Vancouver that flight exposures are likely correlated with rates of transmission in the location where the flight originates, meaning B.C.'s case rate is only partly responsible for flights passing through B.C. airports with the coronavirus on board. 

Another factor is the sheer volume of air travel, which has increased in 2021 compared to 2020, though it remains down significantly at Vancouver International Airport. In July, the most recent month for which figures are available, B.C.'s largest airport served only a fraction of the number of passengers it had in July 2019. 

September's flight exposures came during a month in which Canada relaxed travel restrictions for international visitors.

After allowing fully vaccinated travellers from the U.S. to visit Canada for non-essential reasons without quarantining in early August, the federal government extended that welcome to fully vaccinated travellers from other countries in early September

International travellers bound for Canada have also been required to provide proof of a negative test before boarding since January of this year

No testing requirement currently exists for domestic travellers, nor is proof of vaccination required to board flights within Canada, though the federal government said Wednesday that vaccination would be required for domestic travellers by Oct. 30

Three-quarters of the COVID-19 exposures on airplanes in B.C. since the pandemic began have been on domestic flights. In September, 182 of the 251 flights with exposures were domestic, while the remaining 69 were international.

Last month, a Vancouver infectious disease specialist told CTV News all passengers should be required to provide a negative test and proof of vaccination before boarding an airplane, regardless of the destination.

Even then, there will still be some risk of COVID-19 transmission on flights, said Dr. Brian Conway, medical director of the Vancouver Infectious Diseases Centre.

"We currently live in a world of COVID," Conway said, at the time. "It is highly likely that we will live in a world of COVID for the foreseeable future, so these (flight exposures) are occurrences that will happen on an ongoing basis. They will not, not happen."