Effectiveness of COVID-19 vaccines over time prior to Omicron emergence in Ontario, Canada : test-negative design study

Chung, Hannah; Brown, Kevin A.; Buchan, Sarah A.; Fell, Deshayne B.; Fong, Cindy; Gubbay, Jonathan B.; Nasreen, Sharifa; Schwartz, Kevin L.; Sundaram, Maria E.; Tadrous, Mina; Wilson, Kumanan; Wilson, Sarah E.; Kwong, Jeffrey C.; Canadian Immunization Research Network (CIRN) Provincial Collaborative Network Investigators; Austin, Peter C.

doi:https://open-science.canada.ca/handle/123456789/3164

Effectiveness of COVID-19 vaccines over time prior to Omicron emergence in Ontario, Canada : test-negative design study

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dc.contributor.author: Chung, Hannah; Brown, Kevin A.; Buchan, Sarah A.; Fell, Deshayne B.; Fong, Cindy; Gubbay, Jonathan B.; Nasreen, Sharifa; Schwartz, Kevin L.; Sundaram, Maria E.; Tadrous, Mina; Wilson, Kumanan; Wilson, Sarah E.; Kwong, Jeffrey C.; Canadian Immunization Research Network (CIRN) Provincial Collaborative Network Investigators; Austin, Peter C.
dc.date.accessioned: 2024-11-18T19:41:36Z
dc.date.available: 2024-11-18T19:41:36Z
dc.date.issued: 2022-09-07
dc.description.abstract - en: Background Waning protection from 2 doses of coronavirus disease 2019 (COVID-19) vaccines led to third dose availability in multiple countries even before the emergence of the Omicron variant. Methods We used the test-negative study design to estimate vaccine effectiveness (VE) against any severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, any symptomatic infection, and severe outcomes (COVID-19-related hospitalizations or death) by time since second dose of any combination of BNT162b2, mRNA-1273, and ChAdOx1 between January 11, and November 21, 2021, for subgroups based on patient and vaccine characteristics. Results We included 261 360 test-positive cases (of any SARS-CoV-2 lineage) and 2 783 699 individuals as test-negative controls. VE of 2 mRNA vaccine doses decreased from 90% (95% CI, 90%–90%) 7–59 days after the second dose to 75% (95% CI, 72%–78%) after ≥240 days against infection, decreased from 94% (95% CI, 84%–95%) to 87% (95% CI, 85%–89%) against symptomatic infection, and remained stable (98% [95% CI, 97%–98%] to 98% [95% CI, 96%–99%]) against severe outcomes. Similar trends were seen with heterologous ChAdOx1 and mRNA vaccine schedules. VE estimates for dosing intervals <35 days were lower than for longer intervals (eg, VE of 2 mRNA vaccines against symptomatic infection at 120–179 days was 86% [95% CI, 85%–88%] for dosing intervals <35 days, 92% [95% CI, 91%–93%] for 35–55 days, and 91% [95% CI, 90%–92%] for ≥56 days), but when stratified by age group and subperiod, there were no differences between dosing intervals. Conclusions Before the emergence of Omicron, VE of any 2-dose primary series, including heterologous schedules and varying dosing intervals, decreased over time against any infection and symptomatic infection but remained high against severe outcomes.
dc.description.sponsorship: This work was supported by the Canadian Immunization Research Network (CIRN) through a grant from the Public Health Agency of Canada and the Canadian Institutes of Health Research (CNF 151944). This project was also supported by funding from the Public Health Agency of Canada through the Vaccine Surveillance Working Party and the COVID-19 Immunity Task Force. This study was also supported by ICES, which is funded by an annual grant from the Ontario Ministry of Health (MOH). J.C.K. is supported by a Clinician-Scientist Award from the University of Toronto Department of Family and Community Medicine. P.C.A. is supported by a Mid-Career Investigator Award from the Heart and Stroke Foundation. This study was supported by ICES, which is funded by an annual grant from the Ontario Ministry of Health (MOH) and the Ministry of Long-Term Care (MLTC). This study was supported by the Ontario Health Data Platform (OHDP), a Province of Ontario initiative to support Ontario's ongoing response to COVID-19 and its related impacts.
dc.identifier.doi: https://doi.org/10.1093/ofid/ofac449
dc.identifier.issn: 2328-8957
dc.identifier.pubmedID: 36147595
dc.identifier.uri: https://open-science.canada.ca/handle/123456789/3164
dc.language.iso: en
dc.publisher - en: Oxford Academic
dc.rights - en: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
dc.rights - fr: Creative Commons Attribution - Pas d'utilisation commerciale - Pas de modification 4.0 International (CC BY-NC-ND 4.0)
dc.rights.uri - en: https://creativecommons.org/licenses/by-nc-nd/4.0/
dc.rights.uri - fr: https://creativecommons.org/licenses/by-nc-nd/4.0/deed.fr
dc.subject - en: Health; Coronavirus diseases
dc.subject - fr: Santé; Maladie à coronavirus
dc.subject.en - en: Health; Coronavirus diseases
dc.subject.fr - fr: Santé; Maladie à coronavirus
dc.title - en: Effectiveness of COVID-19 vaccines over time prior to Omicron emergence in Ontario, Canada : test-negative design study
dc.type - en: Article
dc.type - fr: Article
local.acceptedmanuscript.articlenum: ofac449
local.article.journalissue: 9
local.article.journaltitle - en: Open Forum Infectious Diseases
local.article.journalvolume: 9
local.pagination: 1-11
local.peerreview - en: Yes
local.peerreview - fr: Oui

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