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Absolute and Relative Vaccine Effectiveness of Primary and Booster Series of COVID-19 Vaccines (mRNA and Adenovirus Vector) Against COVID-19 Hospitalizations in the United States, December 2021–April 2022
Journal article   Open access   Peer reviewed

Absolute and Relative Vaccine Effectiveness of Primary and Booster Series of COVID-19 Vaccines (mRNA and Adenovirus Vector) Against COVID-19 Hospitalizations in the United States, December 2021–April 2022

Nathaniel M Lewis, Nancy Murray, Katherine Adams, Diya Surie, Manjusha Gaglani, Adit A Ginde, Tresa McNeal, Shekhar Ghamande, David J Douin, H Keipp Talbot, …
Open forum infectious diseases, Vol.10(1), ofac698
01/2023
DOI: 10.1093/ofid/ofac698
PMCID: PMC9868348
PMID: 36695662
url
https://doi.org/10.1093/ofid/ofac698View
Published (Version of record) Open Access

Abstract

Background Coronavirus disease 2019 (COVID-19) vaccine effectiveness (VE) studies are increasingly reporting relative VE (rVE) comparing a primary series plus booster doses with a primary series only. Interpretation of rVE differs from traditional studies measuring absolute VE (aVE) of a vaccine regimen against an unvaccinated referent group. We estimated aVE and rVE against COVID-19 hospitalization in primary-series plus first-booster recipients of COVID-19 vaccines. Methods Booster-eligible immunocompetent adults hospitalized at 21 medical centers in the United States during December 25, 2021–April 4, 2022 were included. In a test-negative design, logistic regression with case status as the outcome and completion of primary vaccine series or primary series plus 1 booster dose as the predictors, adjusted for potential confounders, were used to estimate aVE and rVE. Results A total of 2060 patients were analyzed, including 1104 COVID-19 cases and 956 controls. Relative VE against COVID-19 hospitalization in boosted mRNA vaccine recipients versus primary series only was 66% (95% confidence interval [CI], 55%–74%); aVE was 81% (95% CI, 75%–86%) for boosted versus 46% (95% CI, 30%–58%) for primary. For boosted Janssen vaccine recipients versus primary series, rVE was 49% (95% CI, −9% to 76%); aVE was 62% (95% CI, 33%–79%) for boosted versus 36% (95% CI, −4% to 60%) for primary. Conclusions Vaccine booster doses increased protection against COVID-19 hospitalization compared with a primary series. Comparing rVE measures across studies can lead to flawed interpretations of the added value of a new vaccination regimen, whereas difference in aVE, when available, may be a more useful metric.
absolute vaccine effectiveness booster vaccine series COVID-19 primary vaccine series relative vaccine effectiveness

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