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SARS-CoV-2 Seroprevalence During the First and Second Pandemic Waves in Canada

30 Pages Posted: 12 Aug 2021

See all articles by Xuyang Tang

Xuyang Tang

University of Toronto - Centre for Global Health Research

Abha Sharma

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

Maria Pasic

St. Joseph’s Health Centre, Unity Health

Patrick Brown

University of Toronto - Centre for Global Health Research

Karen Colwill

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

Hellen Gelband

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

Aiyush Bansal

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 Tam

University of Toronto - Centre for Global Health Research

Kento Abe

University of Toronto - Mount Sinai Hospital, Toronto

Bhavisha Rathod

Mount Sinai School of Medicine

Mahya Fazel-Zarandi

University of Toronto - Mount Sinai Hospital, Toronto

Jenny Wang

Mt. Sinai Hospital - Samuel Lunenfeld Research Institute; University of Toronto - Mount Sinai Hospital, Toronto

Mariam Iskilova

University of Toronto - Mount Sinai Hospital, Toronto

Adrian Pasculescu

Mt. Sinai Hospital - Samuel Lunenfeld Research Institute; University of Toronto - Mount Sinai Hospital, Toronto

Lauren Caldwell

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

Miriam Barrios-Rodiles

University of Toronto - Mount Sinai Hospital, Toronto

Zahraa Mohammed-Ali

University of Toronto - St. Joseph’s Health Centre

Nandita Vas

University of Toronto - St. Joseph’s Health Centre

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

Vedika Jha

University of Toronto - Centre for Global Health Research

Wilson Suraweera

University of Toronto - Centre for Global Health Research

Varsha Malhotra

University of Toronto - Centre for Global Health Research

Kathy Mastali

University of Toronto - Centre for Global Health Research

Richard Wen

University of Toronto - Centre for Global Health Research

Samir Sinha

University of Toronto - Mount Sinai Hospital, Toronto

Angus Reid

Angus Reid Institute

Anne-Claude Gingras

University of Toronto - Mount Sinai Hospital, Toronto

Pranesh Chakraborty

University of Ottawa

Arthur S. Slutsky

University of Toronto - Unity Health Toronto

Prabhat Jha

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

More...

Abstract

Background: The prevalence of infection in Canada’s COVID-19 viral waves, the predictors of infection, and the durability of antibody responses to infection remain undocumented.

Methods: We organized serial online surveys of a representative group of Canadian adults about their COVID experience in the first (n=19 994; April-July 2020) and second viral wave (n=14 621; October 2020-March 2021). We paired these with IgG analysis of SARS-CoV-2 seroprevalence in self-collected dried blood spots after the first (n=8967) and second (n=7102) waves.

Findings: Canada’s cumulative seroprevalence of SARS-CoV-2 among unvaccinated adults rose from ~2% after the first wave to 7% after the second. The seropositivity pattern was heterogeneous demographically and geographically during the first wave, but more homogeneous by the second (except in the four Atlantic Provinces, cumulative seroprevalence ~3%). Seroprevalence among visible minorities rose sharply from about 2% to >8% from the first to second wave. About a quarter of those reporting COVID symptoms during the second wave were seropositive, and in both waves the odds ratio (OR) of seropositivity for COVID symptoms exceeded six. About one-fifth of seropositives reported no symptoms. Of 134 seropositive adults in the first wave who were retested after the second, 83% (111) remained seropositive at least seven months later. Current smokers and people with a history of diabetes had lower ORs of infection. We calculated the absolute numbers of seropositive adults nationwide, which nearly quadrupled from 0.57 million to 1.90 million, with the largest increases among older adults. Infection fatality rates fell from 3.7 to 2.6/1000 infections, most notably at older ages.

Interpretation: Canada’s COVID pandemic grew substantially between the first and second viral waves. Home-based DBS collection offers a practicable way to document evolving demographic and geographic patterns and to assess the levels and durability of population immunity, including from SARS-CoV-2 vaccination.

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

Declaration of Interest: None to declare.

Ethical Approval: The Ab-C study was approved by the Unity Health Toronto Ethics Review Board.

Suggested Citation

Tang, Xuyang and Sharma, Abha and Pasic, Maria and Brown, Patrick and Colwill, Karen and Colwill, Karen and Gelband, Hellen and Birnboim, Chaim and Nagelkerke, Nico and Bogoch, Isaac and Bansal, Aiyush 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 Tam, Teresa and Abe, Kento and Rathod, Bhavisha and Fazel-Zarandi, Mahya and Wang, Jenny and Wang, Jenny and Iskilova, Mariam and Pasculescu, Adrian and Pasculescu, Adrian and Caldwell, Lauren and Caldwell, Lauren and Barrios-Rodiles, Miriam and Mohammed-Ali, Zahraa and Vas, Nandita and Santhanam, Divya Raman and Cho, Eo Rin and Qu, Kathleen and Jha, Vedika and Suraweera, Wilson and Malhotra, Varsha and Mastali, Kathy and Wen, Richard and Sinha, Samir and Reid, Angus and Gingras, Anne-Claude and Chakraborty, Pranesh and Slutsky, Arthur S. and Jha, Prabhat, SARS-CoV-2 Seroprevalence During the First and Second Pandemic Waves in Canada. Available at SSRN: https://ssrn.com/abstract=3903944 or http://dx.doi.org/10.2139/ssrn.3903944

Xuyang Tang

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

Abha Sharma

University of Toronto

Toronto, Ontario M5S 3G8
Canada

University of Toronto - Centre for Global Health Research

Toronto, Ontario M5B 1W8
Canada

Maria Pasic

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

Patrick Brown

University of Toronto - Centre for Global Health Research

Toronto, Ontario M5B 1W8
Canada

Karen Colwill

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

Toronto, Ontario M5B 1W8
Canada

Sinai Health System Toronto ( email )

Hellen Gelband

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

Toronto, Ontario M5B 1W8
Canada

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

Aiyush Bansal

University of Toronto - Centre for Global Health Research

Toronto, M5B 1W8
Canada

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 Tam

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

Toronto, Ontario M5B 1W8
Canada

Kento Abe

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

00 University Ave
Toronto, Ontario
Canada

Bhavisha Rathod

Mount Sinai School of Medicine ( email )

New York, NY
United States

Mahya Fazel-Zarandi

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

00 University Ave
Toronto, Ontario
Canada

Jenny Wang

Mt. Sinai Hospital - Samuel Lunenfeld Research Institute

Toronto, M5G 1X5
Canada

University of Toronto - Mount Sinai Hospital, Toronto

00 University Ave
Toronto, Ontario
Canada

Mariam Iskilova

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

00 University Ave
Toronto, Ontario
Canada

Adrian Pasculescu

University of Toronto - Mount Sinai Hospital, Toronto

00 University Ave
Toronto, Ontario
Canada

Mt. Sinai Hospital - Samuel Lunenfeld Research Institute

Toronto, M5G 1X5
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

Zahraa Mohammed-Ali

University of Toronto - St. Joseph’s Health Centre ( email )

Canada

Nandita Vas

University of Toronto - St. Joseph’s Health Centre ( email )

Canada

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

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

Varsha Malhotra

University of Toronto - Centre for Global Health Research

Toronto, Ontario M5B 1W8
Canada

Kathy Mastali

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

University of Toronto - Mount Sinai Hospital, Toronto

00 University Ave
Toronto, Ontario
Canada

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

University of Toronto - Unity Health Toronto ( email )

Toronto
Canada

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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