Stringency of Containment and Closures on the Growth of SARS-CoV-2 in Canada prior to Accelerated Vaccine Roll-Out

30 Pages Posted: 29 Oct 2021 Last revised: 10 Jan 2022

See all articles by David M. Vickers

David M. Vickers

University of Calgary - Centre for Health Informatics

Stefan Baral

John Hopkins University

Sharmistha Mishra

University of Toronto - MAP-Centre for Urban Health Solutions

Jeff Kwong

University of Toronto - Dalla Lana School of Public Health

Maria Sundaram

Queen's University - Institute for Clinical Evaluative Sciences

Alan Katz

University of Manitoba - Department of Community Health Sciences (CHS); University of Manitoba - Manitoba Centre for Health Policy

Andrew Calzavara

Queen's University - Institute for Clinical Evaluative Sciences

Mathieu Maheu-Giroux

McGill University - Epidemiology, Biostatistics, & Occupational Health

David L. Buckeridge

McGill University - School of Population and Global Health

Tyler Williamson

University of Calgary

Date Written: October 21, 2021

Abstract


Background: Many studies have examined the effectiveness of non-pharmaceutical interventions (NPIs) on SARS-CoV-2 transmission worldwide. However, less attention has been devoted to understanding the limits of NPIs across the course of the pandemic and along a continuum of their stringency. In this study, we explore the relationship between the growth of SARS-CoV-2 cases and an NPI stringency index across Canada prior to accelerated vaccine roll-out.

Methods: We conducted an ecological time-series study of daily SARS-CoV-2 case growth in Canada from February 2020 to February 2021. Our outcome was a back-projected version of the daily growth ratio in a stringency period (i.e., a 10-point range of the stringency index) relative to the last day of the previous period. We examined the trends in case growth using a linear mixed effects model accounting for stringency period, province, and mobility in public domains.

Results: Case growth declined, rapidly, by 37–50% and began plateauing within the first two weeks of the first wave, irrespective of the starting values of the stringency index. The effects of changing stringency periods across each wave were not immediate and were more-quickly observed in the first wave (at nine days) than in the second (at 23 days). The largest decreasing trends from our mixed effects model occurred over the first stringency period in each province, at a mean index value of 25.2 out of 100.

Conclusions: There was a negative correlation between NPI stringency and growth of SARS-CoV-2 that diminished throughout the course of Canada’s epidemic. We suggest that individual- and network-level risk factors need to guide the use of NPIs in future epidemics.

Note:
Funding: This study was supported by ICES, which is funded by an annual grant from the Ontario Ministry of Health and the Ministry of Long-Term Care.

Declaration of Interests: Mathieu Maheu-Giroux reports a contractual agreement with the Institut national de santé publique du Québec and Institut d’excellence en sante et en service sociaux. All remaining authors have no competing interests to declare.

Ethics Approval Statement: The data used in this study are publicly available aggregated (i.e., non-identifiable) time series from provincial COVID-19 surveillance dashboards and the Oxford COVID-19 Government Response Tracker. Under Article 2.2 of Canada’s Tri-Council 2018 Policy Statement on the Ethical Conduct for Research Involving Humans these publicly available datasets do not require Ethics approval for access or analysis.

Keywords: COVID-19, Non-pharmaceutical interventions, Ceiling Effects, Stringency Index, Epidemiology

JEL Classification: I18

Suggested Citation

Vickers, David M. and Baral, Stefan and Mishra, Sharmistha and Kwong, Jeff and Sundaram, Maria and Katz, Alan and Calzavara, Andrew and Maheu-Giroux, Mathieu and Buckeridge, David L. and Williamson, Tyler, Stringency of Containment and Closures on the Growth of SARS-CoV-2 in Canada prior to Accelerated Vaccine Roll-Out (October 21, 2021). Available at SSRN: https://ssrn.com/abstract=3947387 or http://dx.doi.org/10.2139/ssrn.3947387

David M. Vickers (Contact Author)

University of Calgary - Centre for Health Informatics ( email )

Canada

Stefan Baral

John Hopkins University ( email )

Baltimore, MD
United States

Sharmistha Mishra

University of Toronto - MAP-Centre for Urban Health Solutions ( email )

209 Victoria St
Toronto, Ontario M5B 1T8
Canada

Jeff Kwong

University of Toronto - Dalla Lana School of Public Health

Toronto, Ontario
Canada

Maria Sundaram

Queen's University - Institute for Clinical Evaluative Sciences

Canada

Alan Katz

University of Manitoba - Department of Community Health Sciences (CHS) ( email )

750 Bannatyne Ave
Winnipeg, R3E 0W3
Canada

University of Manitoba - Manitoba Centre for Health Policy ( email )

University of Manitoba Bannatyne Campus
Winnipeg
Canada

Andrew Calzavara

Queen's University - Institute for Clinical Evaluative Sciences

Canada

Mathieu Maheu-Giroux

McGill University - Epidemiology, Biostatistics, & Occupational Health ( email )

845 Sherbrook Street West
Montreal, QC H3A 0G4
Canada

David L. Buckeridge

McGill University - School of Population and Global Health ( email )

Montreal, Quebec
Canada

Tyler Williamson

University of Calgary ( email )

University Drive
Calgary, T2N 1N4
Canada

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