{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,21]],"date-time":"2026-06-21T05:35:59Z","timestamp":1782020159551,"version":"3.54.5"},"reference-count":31,"publisher":"Oxford University Press (OUP)","issue":"4","license":[{"start":{"date-parts":[[2022,8,17]],"date-time":"2022-08-17T00:00:00Z","timestamp":1660694400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"funder":[{"DOI":"10.13039\/501100012395","name":"Canadian Immunization Research Network","doi-asserted-by":"crossref","id":[{"id":"10.13039\/501100012395","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/100011094","name":"Public Health Agency of Canada","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100011094","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100008097","name":"University of Toronto Department of Family and Community Medicine","doi-asserted-by":"crossref","id":[{"id":"10.13039\/501100008097","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2023,2,18]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>A major goal of coronavirus disease 2019 (COVID-19) vaccination is to prevent severe outcomes (hospitalizations and deaths). We estimated the effectiveness of messenger RNA (mRNA) and ChAdOx1 COVID-19 vaccines against severe outcomes in 4 Canadian provinces between December 2020 and September 2021.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We conducted this multiprovincial, retrospective, test-negative study among community-dwelling adults aged \u226518 years in Ontario, Quebec, British Columbia, and Manitoba using linked provincial databases and a common study protocol. Multivariable logistic regression was used to estimate province-specific vaccine effectiveness against COVID-19 hospitalization and\/or death. Estimates were pooled using random-effects models.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>We included 2 508 296 tested participants, with 31 776 COVID-19 hospitalizations and 5842 deaths. Vaccine effectiveness was 83% after a first dose and 98% after a second dose against both hospitalization and death (separately). Against severe outcomes, effectiveness was 87% (95% confidence interval [CI], 71%\u201394%) \u226584 days after a first dose of mRNA vaccine, increasing to 98% (95% CI, 96%\u201399%) \u2265112 days after a second dose. Vaccine effectiveness against severe outcomes for ChAdOx1 was 88% (95% CI, 75%\u201394%) \u226556 days after a first dose, increasing to 97% (95% CI, 91%\u201399%) \u226556 days after a second dose. Lower 1-dose effectiveness was observed for adults aged \u226580 years and those with comorbidities, but effectiveness became comparable after a second dose. Two doses of vaccines provided very high protection for both homologous and heterologous schedules and against Alpha, Gamma, and Delta variants.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Two doses of mRNA or ChAdOx1 vaccine provide excellent protection against severe outcomes.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/cid\/ciac634","type":"journal-article","created":{"date-parts":[[2022,8,16]],"date-time":"2022-08-16T23:47:11Z","timestamp":1660693631000},"page":"640-648","source":"Crossref","is-referenced-by-count":18,"title":["Effectiveness of Coronavirus Disease 2019 Vaccines Against Hospitalization and Death in Canada: A Multiprovincial, Test-Negative Design Study"],"prefix":"10.1093","volume":"76","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9793-113X","authenticated-orcid":false,"given":"Sharifa","family":"Nasreen","sequence":"first","affiliation":[{"name":"Dalla Lana School of Public Health, University of Toronto , Toronto, Ontario , Canada"},{"name":"ICES , Toronto, Ontario , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yossi","family":"Febriani","sequence":"additional","affiliation":[{"name":"Centre Hospitalier Universitaire de Qu\u00e9bec-Universit\u00e9 Laval Research Center , Quebec City, Quebec , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"H\u00e9ctor Alexander","family":"Vel\u00e1squez Garc\u00eda","sequence":"additional","affiliation":[{"name":"British Columbia Centre for Disease Control , Vancouver, British Columbia , Canada"},{"name":"School of Population and Public Health, University of British Columbia , Vancouver, British Columbia , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Geng","family":"Zhang","sequence":"additional","affiliation":[{"name":"Vaccine and Drug Evaluation Centre, Department of Community Health Sciences, University of Manitoba , Winnipeg, Manitoba , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mina","family":"Tadrous","sequence":"additional","affiliation":[{"name":"ICES , Toronto, Ontario , Canada"},{"name":"Women\u2019s College Hospital , Toronto, Ontario , Canada"},{"name":"Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto, Ontario , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sarah A","family":"Buchan","sequence":"additional","affiliation":[{"name":"Dalla Lana School of Public Health, University of Toronto , Toronto, Ontario , Canada"},{"name":"ICES , Toronto, Ontario , Canada"},{"name":"Public Health Ontario , Toronto, Ontario , Canada"},{"name":"Centre for Vaccine Preventable Diseases, University of Toronto , Toronto, Ontario , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christiaan H","family":"Righolt","sequence":"additional","affiliation":[{"name":"Vaccine and Drug Evaluation Centre, Department of Community Health Sciences, University of Manitoba , Winnipeg, Manitoba , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Salaheddin M","family":"Mahmud","sequence":"additional","affiliation":[{"name":"Vaccine and Drug Evaluation Centre, Department of Community Health Sciences, University of Manitoba , Winnipeg, Manitoba , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Naveed Zafar","family":"Janjua","sequence":"additional","affiliation":[{"name":"British Columbia Centre for Disease Control , Vancouver, British Columbia , Canada"},{"name":"School of Population and Public Health, University of British Columbia , Vancouver, British Columbia , Canada"},{"name":"Centre for Health Evaluation and Outcome Sciences, St Paul\u2019s Hospital , Vancouver, British Columbia , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mel","family":"Krajden","sequence":"additional","affiliation":[{"name":"British Columbia Centre for Disease Control , Vancouver, British Columbia , Canada"},{"name":"Department of Pathology and Laboratory Medicine, University of British Columbia , Vancouver, British Columbia , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gaston","family":"De Serres","sequence":"additional","affiliation":[{"name":"Centre Hospitalier Universitaire de Qu\u00e9bec-Universit\u00e9 Laval Research Center , Quebec City, Quebec , Canada"},{"name":"Institut national de sante publique du Qu\u00e9bec, Biological and Occupational Risks , Quebec City, Quebec , Canada"},{"name":"Department of Social and Preventive Medicine, Faculty of Medicine, Laval University , Quebec City, Quebec , Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeffrey 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