Quirks & Quarks

COVID 19: Can we control the pandemic and move from 'flattening the curve' to 'riding the wave'?

Epidemiologists at the University of Toronto are working on modelling ways we might manage the COVID-19 pandemic after we've "flattened the curve," so we can return to some semblance of a normal life.

Epidemiologists look at how we might control the coronavirus over the long haul

Empty streets, like the intersection of Robson and Granville streets in Vancouver, can't go on forever. (Ben Nelms/CBC)

Epidemiologists at the University of Toronto are working on modelling ways we might manage the COVID-19 pandemic after we've "flattened the curve," so we can return to some semblance of a normal life.

Flattening the curve refers to slowing the growth of the pandemic through physical distancing and other measures that slow the transmission of the coronavirus through the population. This means fewer people are infected at once, which will keep hospitals from being overwhelmed.

It also buys time to ramp up production of medical supplies, test treatments and, in the longer term, develop a vaccine.

But were we to release the restrictions completely, or too soon, infections would rise and crest again, and the disastrous large peak of infections would just have been bumped down the road.

"Just based on the characteristics of how infectious diseases spread, and what we know about coronavirus in particular ... a certain proportion of the population is going to have to be infected before this disease goes away," epidemiologist Ashleigh Tuite told Bob McDonald in an interview with Quirks & Quarks

Surfing a modest wave of infections

Tuite and her colleagues at the Dalla Lana School of Public Health at the University of Toronto have been exploring a modified version of "flattening the curve" that might be called "riding the wave." 

The graph on the left shows an uncontrolled epidemic, and a 'flattened curve.' In the graph on the right, the wavy lines indicate an epidemic controlled by cycles of more and less rigorous intervention over time. (Ashleigh Tuite)

Put simply, they've modelled a path the infection rate could follow that would allow the restoration of some level of physical interaction and normal social and economic activity.

"Instead of having everybody stay at home and work remotely and have children out of school, there's the potential that we may be able to come up with some creative ways to basically return a little bit more to normal," said Tuite.

It requires keeping tight restrictions in place until we've made sure that an early, intense peak of infections isn't going to happen.

The idea then is that we can begin to lift restrictions. By carefully monitoring infection rates with thorough testing and isolation of infected individuals, we attempt to keep infections at a low level. If infection rates start to rise too fast, we may need to temporarily intensify restrictions until the levels drop again.

The resulting graph of infection rates then starts to look like a long, low, repeating wave, as infection rates rise a little, then drop a little over a long period of time.

Restoring some level of social and economic normality

The ultimate benefit of this strategy is that some level of normal activity is possible, and infection rates are kept at a low level overall. 

Ashleigh Tuite is an epidemiologist at the Dalla Lana School of Public Health at the University of Toronto. (Ashleigh Tuite)

The researchers hope that, at some point, the development of an effective vaccine will end the wave and bring the pandemic to a close. If that happens, the ultimate result of this kind of intervention might be that a very small part of the population actually gets infected in the end.

Tuite and her team ran their model over two years, at which point it's certainly imaginable that a vaccine might have been developed.

"Over the two-year period, we're talking about five per cent of the population getting infected," Tuite said. 

Tuite cautions that this can only happen if we are diligent in our testing and monitoring of our population. This is especially true if other nations don't manage their own epidemics as effectively as we do. 

"We're going to have to be vigilant and we're going to have to keep responding to the situation that's happening globally," Tuite said.

Written and produced by Jim Lebans

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