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. 2023 Apr 19;10(6):ofad209.
doi: 10.1093/ofid/ofad209. eCollection 2023 Jun.

Effectiveness of the Coronavirus Disease 2019 Bivalent Vaccine

Nabin K Shrestha  1 , Patrick C Burke  2 , Amy S Nowacki  3 , James F Simon  4 , Amanda Hagen  5 , Steven M Gordon  1
Affiliations

Effectiveness of the Coronavirus Disease 2019 Bivalent Vaccine

Nabin K Shrestha et al. Open Forum Infect Dis. .

Abstract

Background: The purpose of this study was to evaluate whether a bivalent coronavirus disease 2019 (COVID-19) vaccine protects against COVID-19.

Methods: The study included employees of Cleveland Clinic in employment when the bivalent COVID-19 vaccine first became available. Cumulative incidence of COVID-19 over the following 26 weeks was examined. Protection provided by vaccination (analyzed as a time-dependent covariate) was evaluated using Cox proportional hazards regression, with change in dominant circulating lineages over time accounted for by time-dependent coefficients. The analysis was adjusted for the pandemic phase when the last prior COVID-19 episode occurred and the number of prior vaccine doses.

Results: Among 51 017 employees, COVID-19 occurred in 4424 (8.7%) during the study. In multivariable analysis, the bivalent-vaccinated state was associated with lower risk of COVID-19 during the BA.4/5-dominant (hazard ratio, 0.71 [95% confidence interval, .63-79]) and the BQ-dominant (0.80 [.69-.94]) phases, but decreased risk was not found during the XBB-dominant phase (0.96 [.82-.1.12]). The estimated vaccine effectiveness was 29% (95% confidence interval, 21%-37%), 20% (6%-31%), and 4% (-12% to 18%), during the BA.4/5-, BQ-, and XBB-dominant phases, respectively. The risk of COVID-19 also increased with time since the most recent prior COVID-19 episode and with the number of vaccine doses previously received.

Conclusions: The bivalent COVID-19 vaccine given to working-aged adults afforded modest protection overall against COVID-19 while the BA.4/5 lineages were the dominant circulating strains, afforded less protection when the BQ lineages were dominant, and effectiveness was not demonstrated when the XBB lineages were dominant.

Keywords: COVID-19; SARS-CoV-2; bivalent vaccine; effectiveness; vaccines.

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Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts.

Figures

Figure 1.
Figure 1.
Cumulative incidence of coronavirus disease 2019 (COVID-19) for study participants stratified by the pandemic phase when the participant's last prior COVID-19 episode occurred. Day 0 was 12 September 2022, the date the bivalent vaccine was first offered to employees. Point estimates and 95% confidence intervals are jittered along the x-axis to improve visibility.
Figure 2.
Figure 2.
Cumulative incidence of coronavirus disease 2019 (COVID-19) for study participants stratified by the number of COVID-19 vaccine doses previously received. Day 0 was 12 September 2022, the date the bivalent vaccine was first offered to employees. Point estimates and 95% confidence intervals are jittered along the x-axis to improve visibility.
Figure 3.
Figure 3.
Simon-Makuch plot comparing the cumulative incidence of coronavirus disease 2019 (COVID-19) for the bivalent-vaccinated and non–bivalent-vaccinated states. Day 0 was 12 September 2022, the date the bivalent vaccine was first offered to employees. Point estimates and 95% confidence intervals are jittered along the x-axis to improve visibility.
See this image and copyright information in PMC

References

    1. Polack FP, Thomas SJ, Kitchin N, et al. . Safety and efficacy of the BNT162b2 mRNA COVID-19 vaccine. N Engl J Med 2020; 383:2603–15. - PMC - PubMed
    1. Baden LR, El Sahly HM, Essink B, et al. . Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. N Engl J Med 2021; 384:403–16. - PMC - PubMed
    1. Dagan N, Barda N, Kepten E, et al. . BNT162b2 mRNA COVID-19 vaccine in a nationwide mass vaccination setting. N Engl J Med 2021; 384:1412–23. - PMC - PubMed
    1. Haas EJ, Angulo FJ, McLaughlin JM, et al. . Impact and effectiveness of mRNA BNT162b2 vaccine against SARS-CoV-2 infections and COVID-19 cases, hospitalisations, and deaths following a nationwide vaccination campaign in Israel: an observational study using national surveillance data. Lancet 2021; 397:1819–29. - PMC - PubMed
    1. Shrestha NK, Nowacki AS, Burke PC, Terpeluk P, Gordon SM. Effectiveness of mRNA COVID-19 vaccines among employees in an American healthcare system. medRxiv [Preprint: not peer reviewed]. 10 August2021. Available from: https://www.medrxiv.org/content/10.1101/2021.06.02.21258231v1. - DOI