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COVID Symptoms, Seroprevalence, and Mortality During the First Wave of SARS-CoV-2 in Canada

17 Pages Posted: 25 Jan 2021

See all articles by Xuyang Tang

Xuyang Tang

University of Toronto - Centre for Global Health Research

Abha Sharma

Centre for Global Health Research, Unity Health Toronto

Maria Pasic

St. Joseph’s Health Centre, Unity Health

Karen Colwill

Sinai Health Toronto; University of Toronto - Centre for Global Health Research

Chaim Birnboim

University of Toronto - Centre for Global Health Research

Nico Nagelkerke

University of Toronto - Centre for Global Health Research

Isaac Bogoch

University of Toronto, Toronto, Canada - Department of Medicine

Craig Schultz

University of Toronto - Centre for Global Health Research

Leslie Newcombe

University of Toronto - Centre for Global Health Research

Justin Slater

University of Toronto - Centre for Global Health Research

Peter Rodriguez

University of Toronto - Centre for Global Health Research

Guowen Huang

University of Toronto - Centre for Global Health Research

Sze Hang Fu

University of Toronto - Centre for Global Health Research

Catherine Meh

University of Toronto - Centre for Global Health Research

Chee Nee Wu

University of Toronto - Centre for Global Health Research

Rupert Kaul

University of Toronto - University Health Network

Marc-André Langlois

University of Ottawa - Department of Biochemistry, Microbiology and Immunology

Ed Morawski

Angus Reid Institute

Andy Hollander

Angus Reid Institute

Demetre Eliopoulos

Angus Reid Institute

Benjamin Aloi

Angus Reid Institute

Teresa Lambe

University of Oxford - The Jenner Institute

Kento Abe

University of Toronto - Mount Sinai Hospital, Toronto

Lauren Caldwell

Sinai Health Toronto; University of Toronto - Mount Sinai Hospital, Toronto

Miriam Barrios-Rodiles

University of Toronto - Mount Sinai Hospital, Toronto

Mahya Fazel-Zarandi

University of Toronto - Mount Sinai Hospital, Toronto

Ronald Weingust

St. Joseph’s Health Centre, Unity Health

Jenny Wang

Sinai Health Toronto

Bhavisha Rathod

Mount Sinai School of Medicine

Divya Raman Santhanam

University of Toronto - Centre for Global Health Research

Eo Rin Cho

Centre for Global Health Research, Unity Health Toronto

Kathleen Qu

University of Toronto - Centre for Global Health Research

Shreya Jha

Centre for Global Health Research, Unity Health Toronto

Vedika Jha

University of Toronto - Centre for Global Health Research

Wilson Suraweera

University of Toronto - Centre for Global Health Research

Richard Wen

University of Toronto - Centre for Global Health Research

Samir Sinha

Sinai Health Toronto

Angus Reid

Angus Reid Institute

Anne-Claude Gingras

University of Toronto - Mount Sinai Hospital, Toronto

Pranesh Chakraborty

University of Ottawa

Arthur S Slutsky

Unity Health Toronto

Prabhat Jha

University of Toronto - St. Michael's Hospital; University of Toronto - Centre for Global Health Research

More...

Abstract

Background: Canada had substantial mortality from COVID in the first SARS-CoV-2 wave, mostly in nursing homes. Efforts to stem the pandemic (including vaccination, now being introduced) can benefit from direct understanding of the relationship of age-specific mortality to SARS-CoV-2 seroprevalence and from information on asymptomatic infection.

Methods: The Action to Beat Coronavirus (Ab-C) study surveyed a reasonably representative sample of 19,994 adult Canadians about COVID symptoms and analyzed IgG antibodies against SARS-CoV-2 from self-collected dried blood spots (DBS) in 8,967 adults. A sensitive and specific chemiluminescence ELISA detected IgG to the spike trimer. We compared seroprevalence to deaths to establish infection fatality rates (IFRs) and used mortality data to estimate infection levels in nursing home residents.

Findings: The best estimate (high specificity) of adult seroprevalence nationally is 1.7%, but as high as 3.5% (high sensitivity) depending on assay cutoffs. The highest prevalence was in Ontario (2.4-3.9%), the most populous province, and in younger adults aged 18-39 years (2.5-4.4%). Based on mortality, we estimated 13-16% of nursing home residents became infected. The first viral wave infected 0.54-1.08 million adult Canadians, half of whom were <40 years old. The IFR outside nursing homes was 0.20-0.40%, but the COVID death rate in nursing home residents was >70 times higher than comparably-aged adults living in the community. Seropositivity correlated with COVID symptoms, particularly during March. Asymptomatic adults constituted about a quarter of definite seropositives, with a greater proportion in the elderly.

Interpretation: Canada had relatively low infection prevalence and low IFRs in the community, but not in nursing homes, during the first viral wave. The Ab-C study demonstrates the practicability of using self-collected DBS for antibody testing in national surveys to monitor the pandemic and vaccine-induced immunity in the population.

Funding Statement: Pfizer Global Medical, Unity Health Foundation, Canadian COVID-19 Immunity Task Force

Declaration of Interests: We declare no competing interests.

Ethics Approval Statement: Ethics approval was provided by St. Michael's Institutional Review
Board. REB 20-107

Suggested Citation

Tang, Xuyang and Sharma, Abha and Pasic, Maria and Colwill, Karen and Colwill, Karen and Birnboim, Chaim and Nagelkerke, Nico and Bogoch, Isaac and Schultz, Craig and Newcombe, Leslie and Slater, Justin and Rodriguez, Peter and Huang, Guowen and Fu, Sze Hang and Meh, Catherine and Wu, Chee Nee and Kaul, Rupert and Langlois, Marc-André and Morawski, Ed and Hollander, Andy and Eliopoulos, Demetre and Aloi, Benjamin and Lambe, Teresa and Abe, Kento and Caldwell, Lauren and Caldwell, Lauren and Barrios-Rodiles, Miriam and Fazel-Zarandi, Mahya and Weingust, Ronald and Wang, Jenny and Rathod, Bhavisha and Santhanam, Divya Raman and Cho, Eo Rin and Qu, Kathleen and Jha, Shreya and Jha, Vedika and Suraweera, Wilson and Wen, Richard and Sinha, Samir and Reid, Angus and Gingras, Anne-Claude and Chakraborty, Pranesh and Slutsky, Arthur S and Jha, Prabhat, COVID Symptoms, Seroprevalence, and Mortality During the First Wave of SARS-CoV-2 in Canada. Available at SSRN: https://ssrn.com/abstract=3752659 or http://dx.doi.org/10.2139/ssrn.3752659

Xuyang Tang

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Abha Sharma

Centre for Global Health Research, Unity Health Toronto

Maria Pasic

St. Joseph’s Health Centre, Unity Health ( email )

Karen Colwill

University of Toronto - Centre for Global Health Research ( email )

Toronto, Ontario M5B 1W8
Canada

Sinai Health Toronto ( email )

Chaim Birnboim

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Nico Nagelkerke

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Isaac Bogoch

University of Toronto, Toronto, Canada - Department of Medicine ( email )

Toronto
Canada

Craig Schultz

University of Toronto - Centre for Global Health Research

Leslie Newcombe

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Justin Slater

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Peter Rodriguez

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Guowen Huang

University of Toronto - Centre for Global Health Research

Toronto, Ontario M5B 1W8
Canada

Sze Hang Fu

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Catherine Meh

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Chee Nee Wu

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Rupert Kaul

University of Toronto - University Health Network

101 College Street
Toronto, ON M5G 1L7
Canada

Marc-André Langlois

University of Ottawa - Department of Biochemistry, Microbiology and Immunology ( email )

Ottawa
Canada

Ed Morawski

Angus Reid Institute ( email )

Canada

Andy Hollander

Angus Reid Institute ( email )

Canada

Demetre Eliopoulos

Angus Reid Institute ( email )

Canada

Benjamin Aloi

Angus Reid Institute ( email )

Canada

Teresa Lambe

University of Oxford - The Jenner Institute ( email )

Old Road Campus Research Building Roosevelt Drive
Oxford, Oxfordshire OX3 7DQ
United Kingdom

Kento Abe

University of Toronto - Mount Sinai Hospital, Toronto ( email )

00 University Ave
Toronto, Ontario
Canada

Lauren Caldwell

University of Toronto - Mount Sinai Hospital, Toronto ( email )

00 University Ave
Toronto, Ontario
Canada

Sinai Health Toronto ( email )

Miriam Barrios-Rodiles

University of Toronto - Mount Sinai Hospital, Toronto ( email )

00 University Ave
Toronto, Ontario
Canada

Mahya Fazel-Zarandi

University of Toronto - Mount Sinai Hospital, Toronto ( email )

00 University Ave
Toronto, Ontario
Canada

Ronald Weingust

St. Joseph’s Health Centre, Unity Health ( email )

Jenny Wang

Sinai Health Toronto

Bhavisha Rathod

Mount Sinai School of Medicine ( email )

New York, NY
United States

Divya Raman Santhanam

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Eo Rin Cho

Centre for Global Health Research, Unity Health Toronto ( email )

Kathleen Qu

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Shreya Jha

Centre for Global Health Research, Unity Health Toronto

Vedika Jha

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Wilson Suraweera

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Richard Wen

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Samir Sinha

Sinai Health Toronto

Angus Reid

Angus Reid Institute

Canada

Anne-Claude Gingras

University of Toronto - Mount Sinai Hospital, Toronto ( email )

00 University Ave
Toronto, Ontario
Canada

Pranesh Chakraborty

University of Ottawa

Arthur S Slutsky

Unity Health Toronto ( email )

Prabhat Jha (Contact Author)

University of Toronto - St. Michael's Hospital ( email )

Toronto
Canada

University of Toronto - Centre for Global Health Research ( email )

Toronto, Ontario M5B 1W8
Canada

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