Quirks & Quarks

We may have passed the tipping point in the COVID-19 coronavirus outbreak

'I think the risk over the next month is reasonably high that we'll start to see this spread in Canada.'

'I think the risk over the next month is reasonably high that we'll start to see this spread in Canada.'

A worshipper wears a face mask to protect against the coronavirus at church on February 26, 2020 in Los Angeles, California. (Mario Tama / Getty Images)

It's looking more and more likely that the opportunity to limit the COVID-19 coronavirus epidemic is disappearing.

Canada's Chief Public Health Officer Theresa Tam said earlier this week, "The window of opportunity for containment … is closing."

Toronto-based epidemiologist Dr. David Fisman told Bob McDonald in an interview on Quirks & Quarks that while it's hard to know for sure, when it comes to the tipping point for this epidemic, "We may have passed it."

On Friday, World Health Organization Director-General Tedros Adhanom Ghebreyesus announced that in response to new cases appearing in several previously unaffected countries, the agency has "increased our assessment of the risk of spread and the risk of impact of COVID-19 to very high at a global level."

Cases of the illness have now been found in more than 50 countries, and China is now not the only nation exporting the disease, as infected travellers from Italy and Iran have also carried the virus to other countries. 

This is particularly worrying for Dr. Fisman: "I think what you see in Iran — and you probably also see this in Italy — ... a very high fraction of deaths, which means that they're recognizing their epidemic late." 

Dr. Fisman is an infectious disease physician and professor of epidemiology at the University of Toronto's Dalla Lana School of Public Health, and worked as a physician through the SARS epidemic in Toronto in 2003.

The epidemic may be much larger in Iran

He and his colleagues have been modelling the spread of the epidemic and their work suggests that Iran, in particular, has massive numbers of undetected or unreported cases.

"Our estimate was, as of last week, that they must have an epidemic somewhere around 20 to 30,000 cases in order for us to be seeing the kinds of importation numbers we're seeing in Canada." 

But Iran — what I think you may be seeing is what happens when you just allow this to run its course, and say we don't have a problem here and stick your head in the sand.- Dr. David Fisman, University of Toronto

He added this has led to several countries in the Middle East, including Kuwait, Afghanistan, Oman, Bahrain and Iraq, discovering cases that seem to have originated in Iran. 

This would make the current outbreak in Iran second only to the outbreak in China, where nearly 80,000 cases have been identified. But the situation in China looks very different from that in Iran, according to Dr. Fisman.

"What you saw over the last couple of weeks was this massive effort at containment in China, which actually seems to have turned the tide," he said. "But Iran — what I think you may be seeing is what happens when you just allow this to run its course, and say we don't have a problem here and stick your head in the sand."

Tehran Municipality workers clean a metro train to avoid the spread of the COVID-19 illness on February 26, 2020. (Atta Kenare / AFP via Getty Images)

A potentially greater threat to Canada: the U.S.

The epidemic in Iran may lead to spread the COVID-19 virus widely in the Middle East, but when it comes to Canada, Iran is not the source Dr. Fisman and many of his colleagues are most concerned about. Canada is relatively unconnected with Iran, which makes it possible we can successfully deal with the flow of infected people from that nation.

"I think for Canada, the place we're really connected to is the United States," he said. While he has great respect for his public health colleagues in the U.S., "Some of the politics there really looks ... from this side of the border, like it might be interfering with their outbreak response."

He also points to technical problems the U.S. Centers for Disease Control has had with testing kits, that may have hampered their ability to test as thoroughly as we're doing in Canada, which, he said, "To my mind suggests they're probably missing a lot more cases than we are."

U.S. President Donald Trump named Vice President Mike Pence as the leader of his coronavirus task force during a news conference at the White House February 26, 2020. (Chip Somodevilla / Getty Images)

Early detection could be key to containing outbreak

To control the outbreak if it arrives in Canada, the key may be early detection, or "case finding." This involves detecting COVID-19 cases in their early stages, and isolating infected individuals before they can spread the infection widely in the community.

"What we don't want in Canada is for us to identify that this is spreading in the community because we have a hospital outbreak — because hospital outbreaks are what we experienced with SARS. And that's sort of a real negative vortex," said Dr. Fisman. 

"All of a sudden you have patients and health care workers sick and the hospitals taken down. So that does two things: that amplifies cases, but it also impedes your ability to control this because hospitals are an important resource for care and control."

Dr. Fisman also suggests that an important element of controlling the impact of a potential epidemic is making sure that if it spreads, it spreads as slowly as possible.

"Do we want the cases to come all at once or do we want them to come more gradually? We probably want them to come more gradually because then our health care system isn't flooded and overwhelmed."

A pedestrian wears a protective mask as she walks in the winter weather downtown in Toronto on Wednesday, February 26, 2020. (Nathan Denette/The Canadian Press)

Engaging in social distancing to slow spread

Dr. Fisman points to advice from U.K. based mathematical epidemiologist, Steve Riley, for concrete advice on how to "flatten" the spread of an epidemic, and it's a simple idea: we may have to engage in rigourous "social distancing," or limiting our contacts, and thus limiting opportunities for infection with other people.

In a Twitter post, Riley wrote, "Our social contacts influence greatly whether we catch a respiratory virus. Therefore the presence of this virus has to change our social contacts and hence have economic impact."

I think the risk over the next month is reasonably high that we'll start to see this spread in Canada.- Dr. David Fisman, University of Toronto

This might mean cancelling public gatherings and public events as China has done, or closing schools as Japan has announced it will do. This could have major economic and social impact on things like religious or political gatherings or sporting events.

A month ago when Dr. Fisman first appeared on Quirks & Quarks, he suggested the risk to Canadians at the time from COVID-19 was "zero." The situation, he said, has changed. 

"I don't know what the risk is as of today. I think the risk over the next month is reasonably high that we'll start to see this spread in Canada."

Produced and written by Jim Lebans


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