Clinical Investigations

Association Between Vaccination Status and Outcomes in Patients Admitted to the ICU With COVID-19*

van Diepen, Sean MD, MSc^1,2,3; McAlister, Finlay A. MD, MSc^2,4,5; Chu, Luan Manh PhD^4,6; Youngson, Erik MMath^4,6; Kaul, Padma PhD^2,4; Kadri, Sameer S. MD, MSc⁷

Author Information

¹ Department of Critical Care Medicine, University of Alberta, Edmonton, AB, Canada.

² The Canadian VIGOUR Centre, University of Alberta, Edmonton, AB, Canada.

³ Division of Cardiology, Department of Medicine, University of Alberta, Edmonton, AB, Canada.

⁴ The Alberta Strategy for Patient Oriented Research Support Unit, AB, Canada.

⁵ Division of General Internal Medicine, Department of Medicine, University of Alberta, Edmonton, AB, Canada.

⁶ Provincial Research Data Services, Alberta Health Services, Edmonton, AB, Canada.

⁷ Critical Care Medicine Department, NIH Clinical Center, Bethesda, MD.

*See also p. 1272.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (http://journals.lww.com/ccmjournal).

The Alberta Strategy for Patient-Oriented Research Support Unit is supported by grants from Canadian Institutes for Health Research, Alberta Innovates, and the University Hospital Foundation, Edmonton, Alberta, Canada.

Dr. McAlister received support for article research from the Canadian Institutes of Health Research. Dr. Kadri receives salary support from the Society of Critical Care Medicine for his role as Associate Editor for Critical Care Medicine; he received support for article research from the National Institutes of Health (NIH); he disclosed government work. The analyses, interpretation, statements and conclusions contained herein are those of the researchers and do not represent the views of the NIH, or the U.S. Government or Government of Ontario, the funding or data sources. The remaining authors have disclosed that they do not have any potential conflicts of interest.

To comply with Alberta’s Health Information Act and the legal data-sharing agreements between the investigators and Alberta Health Services/Alberta Health, the dataset used for this study cannot be made publicly available.

For information regarding this article, E-mail: [email protected]

Critical Care Medicine 51(9):p 1201-1209, September 2023. | DOI: 10.1097/CCM.0000000000005928

Abstract

OBJECTIVES:

Although COVID-19 vaccines can reduce the need for intensive care unit admission in COVID-19, their effect on outcomes in critical illness remains unclear. We evaluated outcomes in vaccinated patients admitted to the ICU with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and the association between vaccination and booster status on clinical outcomes.

DESIGN:

Retrospective cohort.

SETTING AND PATIENTS:

All patients were admitted to an ICU between January 2021 (after vaccination was available) and July 2022 with a diagnosis of COVID-19 based on a SARS-CoV-2 polymerase chain reaction test in Alberta, Canada.

INTERVENTIONS:

None.

MEASUREMENT:

The propensity-matched primary outcome of all-cause in-hospital mortality was compared between vaccinated and unvaccinated patients, and vaccinated patients were stratified by booster dosing. Secondary outcomes were mechanical ventilation (MV) duration ICU length of stay (LOS).

MAIN RESULTS:

The study included 3,293 patients: 743 (22.6%) were fully vaccinated (54.6% with booster), 166 (5.0%) were partially vaccinated, and 2,384 (72.4%) were unvaccinated. Unvaccinated patients were more likely to require invasive MV (78.4% vs 68.2%), vasopressor use (71.1% vs 66.6%), and extracorporeal membrane oxygenation (2.1% vs 0.5%). In a propensity-matched analysis, in-hospital mortality was similar (31.8% vs 34.0%, adjusted odds ratio [OR], 1.25; 95% CI, 0.97–1.61), but median duration MV (7.6 vs 4.7 d; p < 0.001) and ICU LOS (6.6 vs 5.2 d; p < 0.001) were longer in unvaccinated compared to fully vaccinated patients. Among vaccinated patients, greater than or equal to 1 booster had lower in-hospital mortality (25.5% vs 40.9%; adjusted OR, 0.50; 95% CI, 0.0.36–0.68) and duration of MV (3.8 vs 5.6 d; p = 0.025).

CONCLUSIONS:

Nearly one in four patients admitted to the ICU with COVID-19 after widespread COVID-19 vaccine availability represented a vaccine-breakthrough case. Mortality risk remains substantial in vaccinated patients and similar between vaccinated and unvaccinated patients after the onset of critical illness. However, COVID-19 vaccination is associated with reduced ICU resource utilization and booster dosing may increase survivability from COVID-19-related critical illness.