Considering local conditions is the safest and fastest way to reopen Canada’s economy

A new study has found that allowing cities and counties to open and close independently based on standardized guidelines is the quickest and safest way of restoring the Canadian economy. 

The study found that opening workplaces and schools on a county-by-county basis when the county falls below 4.5 active COVID-19 cases per 100,000 would result in 38 per cent fewer person-days of closure.

It also found that focusing on local openings would result in 75% fewer cases than opening the entire province and that coordination of testing rates would reduce infection by 20 per cent.

The study was conducted by University of Waterloo professor Chris Bauch and his collaborators from the University of Guelph, professor Madhur Anand and their postdoctoral fellow Vadim Karatayev. The study is pending peer review.

"Monitoring cases at the province level obscures local differences: some places are COVID-19 hot spots while others have few cases," said Bauch. "Hence, in order to achieve the same public health goals, the province-wide guidelines would need to be even stricter than county-level guidelines, on account of those hotspots that can reseed other locations with new infections. 

This means more days of workplace and school closures as well as more cases under the province level approach unless the province-wide guidelines are very strict".

The researchers also examined the impact of travel between counties. They found that even for relatively higher assumptions about how much travel there is between counties, the county-by-county reopening approach still works better than the province-wide approach. 

In undertaking the study, the researchers created a simulated network of the 49 census divisions in Ontario. They populated the computational model with Ontario's COVID-19 data, population structures and travel patterns, and the province's commuter data to capture the interconnection between counties.

"Ontario's phased approach to reopening the economy after observing a decline in province-wide cases over a period of weeks, and their other criteria, is sensible," said Bauch. "But some health units in Ontario are experiencing a rise in community-acquired infections and are not ready to reopen their workplaces, while other health units are seeing very few cases per capita.

"Our findings suggest that developing guidelines at the level of individual counties, districts, and municipalities might be safer and quicker, as long as testing and other physical distancing efforts continue," said Bauch. However, if counties do not coordinate their criteria for reopening, or use different testing rates, the benefits of the county-by-county approach are weaker."

The county-by-county approach worked better than a province-wide approach, even when the researchers changed the model's parameters. They, therefore, believe the results might apply more broadly to other Canadian provinces and US states. 

The study, The far side of the COVID-19 epidemic curve: local re-openings based on globally coordinated triggers may work best, co-authored by Waterloo's Faculty of Mathematics professor Bauch, and Guelph's School of Environmental Sciences professor Anand and postdoctoral fellow Karatayev, has been submitted for peer-review and publication.

Note: This research has not yet been peer-reviewed and is being released as part of UWaterloo’s commitment to help inform Canada’s COVID-19 response.

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