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. 2023 Apr 18;227(8):970-976.
doi: 10.1093/infdis/jiac460.

Impact of Vaccination, Prior Infection, and Therapy on Omicron Infection and Mortality

Xiaofeng Wang  1 , Joe Zein  1   2 , Xinge Ji  1 , Dan-Yu Lin  3
Affiliations

Impact of Vaccination, Prior Infection, and Therapy on Omicron Infection and Mortality

Xiaofeng Wang et al. J Infect Dis. .

Abstract

Background: Understanding immunity against Omicron infection and severe outcomes conferred by coronavirus disease 2019 (Covid-19) vaccination, prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and monoclonal antibody therapy will inform intervention strategies.

Methods: We considered 295 691 patients tested for SARS-CoV-2 at Cleveland Clinic between 1 October 2021 and 31 January 2022. We used logistic regression to investigate the association of vaccination and prior infection with the risk of SARS-CoV-2 infection and used Cox regression to investigate the association of vaccination, prior infection, and monoclonal antibody therapy with the risks of intensive care unit (ICU) stay and death.

Results: Vaccination and prior infection were less effective against Omicron than Delta infection but provided strong protection against ICU admission and death. Boosting greatly increased vaccine effectiveness against Omicron infection and severe outcomes, although effectiveness waned rapidly over time. Monoclonal antibody therapy considerably reduced risks of ICU admission and death. The relatively low mortality of the Omicron variant was due to both reduced lethality of this variant and increased population immunity acquired from booster vaccination and previous infection.

Conclusions: Booster vaccination and prior SARS-CoV-2 infection provide strong protection against ICU admission and death from Omicron infection. Monoclonal antibody therapy is also beneficial.

Keywords: COVID-19; SARS-CoV-2; mRNA vaccines; monoclonal antibodies; vaccine boosters; waning immunity.

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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.

Figures

Figure 1.
Figure 1.
Association of COVID-19 vaccination and prior SARS-CoV-2 infection with the risk of infection with the Delta and Omicron variants. The odds ratio estimates are indicated by square symbols and the 95% confidence intervals (CI) are shown by horizontal lines.
Figure 2.
Figure 2.
Kaplan-Meier estimates of the survival probabilities for patients who had tested positive for SARS-CoV-2 during the Delta- and Omicron-predominant periods: (A) all patients; (B) patients not vaccinated or previously infected.
See this image and copyright information in PMC

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