While case numbers of COVID-19 in Toronto have remained fairly steady over the last few weeks, new cases of the virus are consistently entering the city via air travel. 

The federal government maintains a non-exhaustive database of places recent travellers may have been exposed to the virus, such as by airplane, cruise ship or train (any public conveyance), and it indicates that at least one flight from Mexico arrived in Toronto with someone who tested positive for the virus in the past week. 

The information on the webpage is gathered through reports received from provincial and territorial health authorities, international health authorities and public websites, and it only includes data from the last two weeks (between July 23 and today).

Most recently, the database shows that Air Canada flight AC1231 flew into Toronto from Cancun, Mexico on July 31. 

The affected rows on this flight are marked as "unknown" on the database, meaning anyone who was on board that flight could have been exposed and should self-monitor for symptoms.

An additional 37 international flights with infected passengers flew into Toronto between July 15 and 29.

At least four domestic flights with cases on board also flew into Toronto from elsewhere in the country over the last two weeks, including WestJet flight WS506 from Saskatoon on July 31. 

While Canada's borders are mostly closed to non-essential travel and have been since March 18, certain exceptions are in place for Canadian citizens, permanent residents, the immediate family members of Canadian citizens or permanent residents, and some other foreign nationals — making it fairly easy for someone who may not know they have COVID-19 to enter the country. 

Thankfully, Canada's mandatory quarantine law means anyone arriving in the country is required to quarantine for 14 days.