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. 2022 Dec 19;75(12):2186-2192.
doi: 10.1093/cid/ciac325.

Effectiveness of Messenger RNA-based Vaccines During the Emergence of the Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Variant

Aditya Sharma  1   2 , Gina Oda  1   2 , Mark Holodniy  1   2   3
Affiliations
Free PMC article

Effectiveness of Messenger RNA-based Vaccines During the Emergence of the Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Variant

Aditya Sharma et al. Clin Infect Dis. .
Free PMC article

Abstract

Background: We evaluated the effectiveness of mRNA-based vaccines following emergence of SARS-CoV-2 Omicron variant.

Methods: Recipients of a third dose of BNT162b2 or mRNA-1273 ≥180 days after the primary series were matched to primary-series recipients and unvaccinated persons. Participants were followed from 1 December 2021 to 12 March 2022. Outcomes were documented SARS-CoV-2 infection, COVID-19 hospitalization, and COVID-19 death. Effectiveness was calculated from 100-day risks estimated with the Kaplan-Meier estimator.

Results: BNT162b2 and mRNA-1273 groups included 221 267 and 187 507 third-dose recipients, respectively, matched to equal numbers of primary-series recipients and unvaccinated persons. Compared with no vaccination, effectiveness of a third dose of BNT162b2 was 47.8% (95% confidence interval [CI], 45.2-50.3), 81.8% (95% CI, 79.2-84.2), and 89.6% (95% CI, 85.0-93.6) against infection, hospitalization, and death, respectively. Effectiveness of a third dose of BNT162b2 compared with the primary series was 30.1% (95% CI, 26.2-33.7), 61.4% (95% CI, 55.0-67.1), and 78.8% (95% CI, 67.9-87.5) against infection, hospitalization, and death, respectively. Effectiveness of a third dose of mRNA-1273 compared with no vaccination was 61.9% (95% CI, 59.4-64.4), 87.9% (95% CI, 85.3-90.2), and 91.4% (95% CI, 86.4-95.6) against infection, hospitalization, and death, respectively. Effectiveness of a third dose of mRNA-1273 compared with the primary series was 37.1% (95% CI, 32.2-41.7), 63.5% (95% CI, 53.7-71.6), and 75.0% (95% CI, 55.4-88.0) against infection, hospitalization, and death, respectively.

Conclusions: BNT162b2 and mRNA-1273 were effective against COVID-19 following emergence of Omicron variant. A third dose provided additional protection over the primary series.

Keywords: COVID-19; Omicron; epidemiology; vaccine.

Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

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