Epidemiologists are researchers who study disease outbreaks—how they happen and how long they’ll last. One of the world’s foremost is Dr. David Fisman, a professor at the University of Toronto’s Dalla Lana School of Public Health and a practicing infectious diseases clinician at Toronto Western Hospital. For the eighth episode of his Eat Move Think podcast, Shaun Francis interviewed Dr. Fisman about how long we’ll have to live with social distancing, when life will return to normal—and what happens next.
Key excerpts (transcript has been synthesized and edited for readability):
1. The moment Dr. Fisman became worried
Dr. Fisman: I was watching the Chinese epidemic curve sort of bend in late January, and got pretty confident that the Chinese were going to contain this. I thought it was very much like SARS, that we’d have a few exportations around the world, but that, you know, people would basically field those fly balls, and it wouldn’t go any further. The wake up for me was in early February when we had our first case in Canada from Iran. And that’s at a time when Iran was officially reporting 55 cases. There’s absolutely no way that you have a 55 case outbreak, and you’re exporting cases all around the world. Those two things don’t add up. So we started to do some analysis. And you know, the numbers suggested, well, Iran must have an outbreak of about 20,000 by that point, for them to be exporting that much… This was the second week of February and at that point, you knew, we were done. This wasn’t going to be contained.
2. The variability of the COVID-19 reproduction number
Dr. Fisman: It’s very similar to SARS. In fact, SARS had a reproduction number in the twos or so, two to three. The difference with SARS… it sort of put up its hand and said, here I am, because most people who had SARS were quite sick. With this thing, part of the difficulty is that it can behave like SARS sometimes. So if COVID gets into the right person, it causes, you know, respiratory failure. But in many people, it seems to cause a relatively mild illness, which makes it very, very difficult to control. [Also, the reproduction number isn’t the same for everyone.] There clearly are a lot of dead ends where no transmission occurs. We’ve seen that with a lot of airplane data, where people have gotten on a flight, turns out they had COVID, but no one on the flight gets infected. And yet, you know, you have these superspreader episodes. The Biogen convention and meeting in Boston, you have someone who generated 70 cases. I think our mining meeting here in Toronto probably was a superspreader event. So you know, it’s sort of this bizarre disease…
3. The cat in the tree analogy: We’re the cat
Dr. Fisman: Once you lock the place down, it takes a couple of weeks to take effect, but it slows it down and it goes away. So then the question is, well, what now? It’s sort of like being a cat chased up a tree by a dog — and the dog is still there, right? If you’re the cat, you’re up the tree, but you don’t want to live the rest of your life in the tree. And unfortunately, that’s sort of the next challenge… Once we get this back under control, how do we climb down? And I think that’s going to be very challenging. The economic challenges are huge. The social challenges are huge… It’s really a mind-blowing series of challenges.
4. Shaun’s question: Do you think we’ll be back to work in May?
Dr. Fisman: I do. I work with an absolutely excellent mathematical epidemiologist by the name of Ashleigh Tuite. And we’ve got a paper that’s going to come out, I think, in CMAJ in a week, modelling this pandemic and trying to figure out, you know, how does the cat climb out of the tree. And what Ashleigh has come up with is this idea of dynamic social distancing. The choke point in our whole healthcare system is the ICU… We have to buy ourselves time to build capacity, but at the same time, we have to allow people to get back to their lives a little bit, to revive the economy. And the way to do that is to watch the ICUs. Shut things down until you have the ICU under control, and then relax things, [while] anticipating that as the ICUs start to fill up again, you’re probably going to need to turn those social distancing measures back on. We’ll get better and better at that. Because simply turning the whole economy off, saying, “Well, you know, in 18 months, we’ll have a vaccine and then we can all go back to work” — I think that’s a non starter. We’re going to have walk this tightrope between economic collapse and healthcare system collapse, which is pretty intimidating, but I do think we’ll probably figure it out in the months to come.
5. Shaun’s question: How do you think Canada has done in managing the disease?
Dr. Fisman: I think Canada’s patchy. Alberta is doing well. British Columbia has done very well. Quebec looks bad, but may be good. Often in situations like this, if you do what they did, which is, they really ramped up surveillance about a week ago to try to find more cases. All of a sudden you find cases everywhere and it looks really bad. That’s actually good. That means you’re starting to see your epidemic for what it is. And you’re actually able to act on that intelligence.
Ontario really troubles me. I think the testing has been a debacle. Without testing for this thing, you can’t see it. So we’re dependent in this province almost entirely on lagging indicators like death, and ICU admissions. In Ontario, we’ve seen a sixfold increase in a week in the number of people with documented COVID who are in ICUs. I think we probably have about 300 beds to spare. Clearly, if we get a six fold increase in the weeks to come, we are now in a New York or Italy kind of scenario… You know, I’m an optimistic person by nature. And I want to be hopeful that we’re not going to go the route of New York or Italy. And I think because Premier Ford was, really, frankly, brave enough and tough enough to put in social distancing before people were scared, I think we’re going to get off lighter than we would have. But I think we’re probably still going to get slammed by this. I think there’s some really ugly stuff in our future.