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Effectiveness of BNT162b2 and mRNA-1273 COVID-19 Vaccines Against Symptomatic SARS-CoV-2 Infection and Severe COVID-19 Outcomes in Ontario, Canada

32 Pages Posted: 14 May 2021

See all articles by Hannah Chung

Hannah Chung

Queen's University - Institute for Clinical Evaluative Sciences

Siyi He

Institute for Clinical Evaluative Sciences (ICES)

Sharifa Nasreen

Queen's University - Institute for Clinical Evaluative Sciences

Maria Sundaram

Queen's University - Institute for Clinical Evaluative Sciences

Sarah Buchan

Public Health Ontario

Sarah Wilson

Public Health Ontario

Branson Chen

Queen's University - Institute for Clinical Evaluative Sciences

Andrew Calzavara

Queen's University - Institute for Clinical Evaluative Sciences

Deshayne Fell

Institute for Clinical Evaluative Sciences (ICES); Children's Hospital of Eastern Ontario Research Institute (CHEO)

Peter C. Austin

Queen's University - Institute for Clinical Evaluative Sciences

Kumanan Wilson

University of Ottawa - Ottawa Hospital Research Institute

Kevin L. Schwartz

Institute for Clinical Evaluative Sciences (ICES)

Kevin A. Brown

Institute for Clinical Evaluative Sciences (ICES)

Jonathan B. Gubbay

Public Health Ontario

Nicole Basta

McGill University

Salaheddin Mahmud

University of Manitoba

Christiaan Righolt

University of Manitoba

Lawrence Svenson

affiliation not provided to SSRN

Shannon MacDonald

affiliation not provided to SSRN

Naveed Janjua

British Columbia Centre for Disease Control

Mina Tadrous

Institute for Clinical Evaluative Sciences (ICES)

Jeffrey C. Kwong

Institute for Clinical Evaluative Sciences (ICES)

Canadian Immunization Research Network (CIRN) Provincial Collaborative Network (PCN) Investigators Group

Independent

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Abstract

Background: We estimated the effectiveness of BNT162b2 and mRNA-1273 vaccines among residents of Ontario, Canada, where a policy to use an up to 16-week interval between doses was adopted in March 2021.

Methods: We conducted a test-negative design study using linked province-wide laboratory, vaccination, and health administrative datasets. We included symptomatic individuals tested for SARS-CoV-2 by RT-PCR between 14 December 2020 and 19 April 2021. Study outcomes included symptomatic infection and associated severe outcomes (hospitalization or death). We estimated adjusted vaccine effectiveness (aVE) using multivariable logistic regression.

Findings: Among 324,033 symptomatic tested individuals, 53,270 (16·4%) were positive for SARS-CoV-2 and 21,272 (6·6%) had received ≥1 dose of mRNA vaccine. Among test-positive cases, 2,479 (4·7%) had a severe outcome. aVE against symptomatic infection ≥14 days after receiving only 1 dose was 60% (95%CI, 57–64%), increasing from 48% (95%CI, 41–54%) at 14–20 days after the first dose to 71% (95%CI, 63–78%) at 35–41 days. aVE ≥7 days after receiving 2 doses was 91% (95%CI, 89–93%). Against severe outcomes, aVE ≥14 days after receiving 1 dose was 70% (95%CI, 60–77%) and aVE ≥7 days after receiving 2 doses was 98% (95%CI, 88–100%). We observed lower aVE against both outcomes after receiving 1 dose for adults aged ≥70 years, but aVE estimates for older adults were comparable to younger adults after 28 days. After 2 doses, we observed high aVE against E484K-positive variants.

Interpretation: Our findings suggest that 2 doses of BNT162b2 and mRNA-1273 vaccines are highly effective against both symptomatic infection and associated severe outcomes for all circulating variants, with effectiveness lower after only a single dose, particularly for older adults shortly after the first dose.

Funding Information: Canadian Institutes of Health Research, Public Health Agency of Canada, Ontario Ministries of Health and Long-Term Care.

Declaration of Interests: KW is CEO of CANImmunize and serves on the data safety board for the Medicago COVID-19 vaccine trial. SMM has received unrestricted research grants from Merck, GlaxoSmithKline, Sanofi Pasteur, Pfizer, and Roche-Assurex for unrelated studies. SMM has received fees as an advisory board member for GlaxoSmithKline, Merck, Pfizer, Sanofi Pasteur, and Seqirus. CHR has received an unrestricted research grant from Pfizer for an unrelated study. The other authors declare no conflicts of interest.

Ethics Approval Statement: ICES is a prescribed entity under Ontario’s Personal Health Information Protection Act (PHIPA). Section 45 of PHIPA authorizes ICES to collect personal health information, without consent, for the purpose of analysis or compiling statistical information with respect to the
management of, evaluation or monitoring of, the allocation of resources to or planning for all or part of the health system. Projects that use data collected by ICES under section 45 of PHIPA, and use no other data, are exempt from REB review. The use of the data in this project is authorized under section 45 and approved by ICES’ Privacy and Legal Office.

Suggested Citation

Chung, Hannah and He, Siyi and Nasreen, Sharifa and Sundaram, Maria and Buchan, Sarah and Wilson, Sarah and Chen, Branson and Calzavara, Andrew and Fell, Deshayne and Austin, Peter C. and Wilson, Kumanan and Schwartz, Kevin L. and Brown, Kevin A. and Gubbay, Jonathan B. and Basta, Nicole and Mahmud, Salaheddin and Righolt, Christiaan and Svenson, Lawrence and MacDonald, Shannon and Janjua, Naveed and Tadrous, Mina and Kwong, Jeffrey C. and Group, Canadian Immunization Research Network (CIRN) Provincial Collaborative Network (PCN) Investigators, Effectiveness of BNT162b2 and mRNA-1273 COVID-19 Vaccines Against Symptomatic SARS-CoV-2 Infection and Severe COVID-19 Outcomes in Ontario, Canada. Available at SSRN: https://ssrn.com/abstract=3845993 or http://dx.doi.org/10.2139/ssrn.3845993

Hannah Chung

Queen's University - Institute for Clinical Evaluative Sciences

Canada

Siyi He

Institute for Clinical Evaluative Sciences (ICES)

Toronto, Ontario M4N M5
Canada

Sharifa Nasreen

Queen's University - Institute for Clinical Evaluative Sciences

Maria Sundaram

Queen's University - Institute for Clinical Evaluative Sciences

Canada

Sarah Buchan

Public Health Ontario

Kingston
Canada

Sarah Wilson

Public Health Ontario

Branson Chen

Queen's University - Institute for Clinical Evaluative Sciences

Canada

Andrew Calzavara

Queen's University - Institute for Clinical Evaluative Sciences

Canada

Deshayne Fell

Institute for Clinical Evaluative Sciences (ICES) ( email )

Toronto, Ontario M4N M5
Canada

Children's Hospital of Eastern Ontario Research Institute (CHEO) ( email )

401 Smyth Road
Ottawa, Ontario K1H 8L1
Canada

Peter C. Austin

Queen's University - Institute for Clinical Evaluative Sciences

Canada

Kumanan Wilson

University of Ottawa - Ottawa Hospital Research Institute ( email )

Ottawa, Ontario
Canada

Kevin L. Schwartz

Institute for Clinical Evaluative Sciences (ICES)

Toronto, Ontario M4N M5
Canada

Kevin A. Brown

Institute for Clinical Evaluative Sciences (ICES)

Toronto, Ontario M4N M5
Canada

Jonathan B. Gubbay

Public Health Ontario

Nicole Basta

McGill University

1001 Sherbrooke St. W
Montreal
Canada

Salaheddin Mahmud

University of Manitoba

501 F.A. Bldg
Winnipeg R3T 5V4, R3T 5V5
Canada

Christiaan Righolt

University of Manitoba

501 F.A. Bldg
Winnipeg R3T 5V4, R3T 5V5
Canada

Lawrence Svenson

affiliation not provided to SSRN

No Address Available

Shannon MacDonald

affiliation not provided to SSRN

Naveed Janjua

British Columbia Centre for Disease Control ( email )

Vancouver, BC
Canada

Mina Tadrous

Institute for Clinical Evaluative Sciences (ICES) ( email )

Toronto, Ontario M4N M5
Canada

Jeffrey C. Kwong (Contact Author)

Institute for Clinical Evaluative Sciences (ICES) ( email )

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