Friday, 03 April, 2020

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Early action on COVID-19 can flatten the curve even more, Toronto researchers urge | CBC News

By now, most people have heard it's important to "flatten the curve" when it comes to COVID-19 infections — and two Toronto-based researchers say the earlier we act, the flatter that curve will be.

David Fisman and Ashleigh Tuite, epidemiologists at the University of Toronto's Dalla Lana School of Public Health, have created a simulation of how early control measures can greatly slow the spread of the novel coronavirus and ease the burden on the health-care system, potentially saving many lives.

These control measures — like cancelling large events, testing aggressively for the virus and isolating suspected cases — can avoid spikes in COVID-19 cases, the researchers say. 

Even though Canada has relatively few confirmed infections — more than 150 as of Friday — the pair says it's not too early to keep it from getting worse.

"If we can preemptively get people to do social distancing, the much easier we'll be able to control this," said Tuite.

The simulator, which uses global infection data, lets you control the start date of the outbreak and when control measures are implemented. You can also see how the infection rate — the basic reproduction number, or R0 — can affect an outcome.

Depending on the severity of the control measures, the R0 changes and the curve of infections flattens.

Here's a simulated curve of COVID-19 cases if nothing is done, compared to one if control measures are put in place as the number of infections rise:

But if measures are enacted earlier, even before the confirmed cases mount, it makes the situation more manageable and puts less stress on the health system:

Their work was also featured Friday in the New York Times.

Too soon to predict cases in Canada

CBC News asked Tuite to provide a simulation with numbers for Canada, but she said it is too soon to make accurate forecasts.

So far, Canada has relatively few confirmed cases of COVID-19, most of which were traced to people who travelled recently or were in contact with those who did. They've also been quickly isolated.

This makes it hard to forecast how high infections in Canada could potentially get, Tuite said.

Once the virus is transmitted within a community, that's when experts can more accurately simulate the numbers. That's because it's estimated each carrier of the virus infects an average of two to three people, Tuite noted, so it becomes a matter of simple exponential math.

"It's easier to predict new cases once that community spread starts happening," said Tuite, noting that might start happening in a few days.

Detection lags make it important to act now

Once someone gets infected, it usually takes five days for symptoms to appear, though it can take as long as 14 days. During that lag, a person can contaminate many others.

"One of the reasons we need to act quickly is because we can't see when someone gets infected and we can't act right away to isolate him," Tuite said.

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