Anyone who boarded GO bus number 40 at Toronto's Pearson International Airport last Wednesday is being urged to contact their doctor or a local public health agency in light of another passenger's recent positive test for COVID-19.

The passenger, a 34-year-old woman, is said to have arrived in Toronto "with a recent travel history to Iran" on February 26. She attended the Mackenzie Health hospital in Richmond Hill the next day with a dry cough, runny nose, shortness of breath and a headache.

Tests later confirmed that the woman, who is now in self-isolation, was infected with the 2019 novel coronavirus.

York Region's medical officer of health, Dr. Karim Kurji, said during a new conference on Saturday that the woman had flown from Iran to Canada via Denmark last week with her husband and child.

Upon arriving in Toronto Wednesday afternoon, she took a GO bus from Terminal 1 at Pearson Airport to the Richmond Hill Centre Terminal.

Anyone who boarded bus 40 at the airport on Feb 26 at 3:55pm to Richmond Hill Centre should reach out to their doctor or public health for advice. We will also do our best to contact those customers who boarded with registered PRESTO cards. 2/3

— Anne Marie Aikins (@AMAwithAMA) March 1, 2020

The woman is said to have been sitting in the upper portion of the double-decker bus around 3:55 p.m. She was not wearing a mask at the time.

Metrolinx spokesperson Anne Marie Aikins told The Star that roughly 35 other people were on the bus at the same time as the woman, and that the provincial transit agency is attempting to make contact with all of them"

"If the card is registered, we are reaching out by email and phone today, we are doing that now," said Aikins of each customer's PRESTO card. "If you got on that bus without using your registered card then we're limited with how we can get in touch with you."

Those who believe they have been exposed to the virus can contact York Region Public Health, but it's important to note that the bus in question had been removed from service and "thoroughly disinfected" by Sunday.

One advantage of @Metrolinx@PRESTOcard system (which I'm not usually a fan of): It's helping track down potential COVID-19 exposures from the York region case. Hope those passengers all registered their presto cards.https://t.co/ou4SFtdRCK

— Christin Scarlett Milloy 👩‍💻📣✍🏻🖖🎮 (@chrinfinity) March 1, 2020

"We're continuing to work very hard to respond to customers and their concerns about the recent case of COVID-19 on a GO bus. We are briefing our staff; bus execs and chief safety officer met with drivers at 5 a.m. to provide info and support," wrote Aikins on Twitter Sunday morning.

"We're also working on expanding the use of a long-acting disinfectant/anti-microbial agent to more vehicles including buses."

Metrolinx has reportedly been testing this long-acting surface disinfectant for three weeks aboard 12 coach trains with satisfatory results.

The Toronto Sun reported on Monday that the transit agency is now spraying all of its buses and trains with something called Microbe Shield Antimicrobial Spray — a substance which puts an extra coating on surfaces to prevent bacteria from sticking for up to a year.

"It's just one kind of extra thing we did. It's important to do everything you can," said Aikins of the pilot test to The Sun in a piece published Monday. "It's non-toxic, doesn't stick, doesn't stink and doesn't stain."

I’m confirming what you’re seeing but this is likely the team applying the new long-acting anti-microbial to our vehicles wearing standard PPE for use of disinfectants.

— Anne Marie Aikins (@AMAwithAMA) March 2, 2020

A total of 18 confirmed cases of the deadly coronavirus are active in Ontario as of Monday afternoon, all of them in the Greater Toronto Area.

The province just announced that it will be implementing a number of enhanced measures to safeguard the public in light of the outbreak.

"Although the risk to Ontarians remains low, it is important that we take decisive steps to prepare for any scenario as this is a quickly evolving situation globally," said Health Minister Christine Elliott this afternoon.

"As we enter this next phase of preparedness, every Ontarian should have full confidence that these efforts by our dedicated public health professionals and health care leaders will continue to keep them safe."