Journal Article

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

Bender, William, Kwon, Jennie H, Lindsell, Christopher J, Rice, Todd W, Wilson, Jennifer G, Gordon, Alexandra June, Lewis, Nathaniel M, Frosch, Anne E, Khan, Akram, Grijalva, Carlos G, Self, Wesley H, Douin, David J, Prekker, Matthew E, Halasa, Natasha, McNeal, Tresa, Monto, Arnold S, Adams, Katherine, Baughman, Adrienne, Gibbs, Kevin W, Mallow, Christopher, Chappell, James D, Steingrub, Jay S, McMorrow, Meredith L, Gaglani, Manjusha, Rivas, Carolina, Ginde, Adit A, Stubblefield, William B, Brown, Samuel M, Mohamed, Amira, Babcock, Hilary M, Hart, Kimberly W, Exline, Matthew C, Mohr, Nicholas M, Hough, Catherine L, Gong, Michelle N, Murray, Nancy, Johnson, Nicholas J, Martin, Emily T, Duggal, Abhijit, Lauring, Adam S, Busse, Laurence W, Qadir, Nida, Zepeski, Anne, Hager, David N, Peltan, Ithan D, Srinivasan, Vasisht, Rhoads, Jillian P, Casey, Jonathan D, Tenforde, Mark W, Ghamande, Shekhar, Patel, Manish M, Talbot, H Keipp, Shapiro, Nathan I, Files, D Clark, Chang, Steven Y, Surie, Diya, Ali, Harith

2023

Overview

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. Although relative vaccine effectiveness can be a useful measure to understand incremental benefit of a vaccine booster regimen compared with a primary series alone, absolute vaccine effectiveness estimates are needed to fully understand their benefit.

• Publisher: Oxford University Press
• Subject: Coronaviruses / COVID-19 vaccines / Hospitalization / Major