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Cited by 307SARS-CoV-2 and COVID-19 ResearchVaccine Coverage and HesitancyCOVID-19 Clinical Research Studies

Effectiveness of BNT162b2 and mRNA-1273 covid-19 vaccines against symptomatic SARS-CoV-2 infection and severe covid-19 outcomes in Ontario, Canada: test negative design study

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Chung, Hannah, He, Siyi, Nasreen, Sharifa, Sundaram, Maria E, Buchan, Sarah A, Wilson, Sarah E, Chen, Branson, Calzavara, Andrew +14 more·2021·BMJ
DOI 10.1136/bmj.n1943PMC PMC8377789

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Abstract

Objective: To estimate the effectiveness of mRNA covid-19 vaccines against symptomatic infection and severe outcomes (hospital admission or death). Design: Test negative design study. Setting: Ontario, Canada between 14 December 2020 and 19 April 2021. Participants: 324 033 community dwelling people aged ≥16 years who had symptoms of covid-19 and were tested for SARS-CoV-2. Interventions: BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) vaccine. Main outcome measures: Laboratory confirmed SARS-CoV-2 by reverse transcription polymerase chain reaction (RT-PCR) and hospital admissions and deaths associated with SARS-CoV-2 infection. Multivariable logistic regression was adjusted for personal and clinical characteristics associated with SARS-CoV-2 and vaccine receipt to estimate vaccine effectiveness against symptomatic infection and severe outcomes. Results: Of 324 033 people with symptoms, 53 270 (16.4%) were positive for SARS-CoV-2 and 21 272 (6.6%) received at least one dose of vaccine. Among participants who tested positive, 2479 (4.7%) were admitted to hospital or died. Vaccine effectiveness against symptomatic infection observed ≥14 days after one dose was 60% (95% confidence interval 57% to 64%), increasing from 48% (41% to 54%) at 14-20 days after one dose to 71% (63% to 78%) at 35-41 days. Vaccine effectiveness observed ≥7 days after two doses was 91% (89% to 93%). Vaccine effectiveness against hospital admission or death observed ≥14 days after one dose was 70% (60% to 77%), increasing from 62% (44% to 75%) at 14-20 days to 91% (73% to 97%) at ≥35 days, whereas vaccine effectiveness observed ≥7 days after two doses was 98% (88% to 100%). For adults aged ≥70 years, vaccine effectiveness estimates were observed to be lower for intervals shortly after one dose but were comparable to those for younger people for all intervals after 28 days. After two doses, high vaccine effectiveness was observed against variants with the E484K mutation. Conclusions: Two doses of mRNA covid-19 vaccines were observed to be highly effective against symptomatic infection and severe outcomes. Vaccine effectiveness of one dose was observed to be lower, particularly for older adults shortly after the first dose.

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  • For vaccine effectiveness against progression from oxygen use to mechanical ventilation or death, additional adjustments were made for use of antivirals, monoclonal antibody therapy, steroids, anti-inflammatory drugs, anticoagulation, and proning; these potential confounders were determined a priori based on published reports.

    “To estimate VE against progression from oxygen use to mechanical ventilation or death among COVID-19 patients, additional adjustments were made for use of antivirals, monoclonal antibody therapy, steroids, anti-inflammatory drugs (tocilizumab or baricitinib), anticoagulation, and proning. These potential confounders were determined a priori based on published reports [8,9,15,17].”

    From COVID-19 vaccine effectiveness against severe COVID-19 requiring oxygen therapy, invasive mechanical ventilation, and death in Japan: A multicenter case-control study (MOTIVATE study) (2024) · cites this paper as [8]

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Authors
Chung, H., He, S., Nasreen, S., Sundaram, M. E., Buchan, S. A., Wilson, S. E., Chen, B., Calzavara, A., Fell, D. B., Austin, P. C., Wilson, K., Schwartz, K. L., Brown, K. A., Gubbay, J. B., Basta, N. E., Mahmud, S. M., Righolt, C. H., Svenson, L. W., MacDonald, S. E., Janjua, N. Z., Tadrous, M., & Kwong, J. C.
Affiliations
  • Institute for Clinical Evaluative Sciences (CA)
  • University of Toronto (CA)
  • University of Ottawa (CA)
  • McGill University (CA)
  • University of Manitoba (CA)
  • University of Alberta (CA)
  • University of British Columbia (CA)
  • University Health Network (CA)
Corresponding author
Kwong, Jeffrey C
ORCID
Venue
BMJ
Publisher
BMJ
Published
2021-08-20
Volume
374
Pages
n1943
ISSN
1756-1833 (ISSN-L)
DOI
10.1136/bmj.n1943
PMC
PMC8377789
OpenAlex
W3194598131
Cited by
307
References
3
Citations by year
2026: 6 · 2025: 15 · 2024: 28 · 2023: 72 · 2022: 144 · 2021: 42
FWCI
22.65
Type
journal article
Language
en
Open access
Licence
Locations
  • BMJ (publishedVersion, cc-by)
  • medRxiv (acceptedVersion, cc-by-nc-nd)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Federal Open Science Repository of Canada / Le Dépôt fédéral de science ouverte du Canada (submittedVersion, cc-by)
  • SUNY Digital Repository Support (State University of New York System) (submittedVersion, cc-by)
Funders
  • Heart and Stroke Foundation of Canada
  • Public Health Agency of Canada (CNF 151944, 151944)
  • Public Health Agency
  • University of Toronto
  • Canadian Immunization Research Network (CNF 151944)
  • Canadian Institutes of Health Research (151944, COVID-19, 151944_1)
  • Department of Family and Community Medicine, University of Toronto
  • National Institute of Allergy and Infectious Diseases (R01AI132496)
Topics
  • Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
  • Social Sciences › Health › Vaccine Coverage and Hesitancy
  • Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
Keywords
BNT162b2, mRNA-1273, COVID-19 vaccines, SARS-CoV-2, vaccine effectiveness, symptomatic infection, hospitalization, COVID-19 mortality, test-negative design, two-dose vaccination, older adults, Ontario, COVID-19 pandemic, SARS-CoV-2 seroprevalence, vaccine hesitancy
MeSH terms
COVID-19, SARS-CoV-2, COVID-19 Vaccines, COVID-19 Nucleic Acid Testing, BNT162 Vaccine, 2019-nCoV Vaccine mRNA-1273, Adolescent, Adult, Aged, Female, Humans, Male, Middle Aged, Ontario, Patient Admission, Treatment Outcome, Young Adult

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