The Impact of the COVID-19 Omicron Variant on Immunocompromised Patients: ICU Admissions and Increased Mortality

Jan Pander; Fabian Termorshuizen; Dylan W de Lange; Wendy Beekman-Hendriks; Josien Lanfermeijer; Ferishta Bakhshi-Raiez; Dave A Dongelmans

doi:10.1007/s40121-025-01122-5

The Impact of the COVID-19 Omicron Variant on Immunocompromised Patients: ICU Admissions and Increased Mortality

Infect Dis Ther. 2025 Apr;14(4):881-888. doi: 10.1007/s40121-025-01122-5. Epub 2025 Mar 14.

Authors

Jan Pander¹, Fabian Termorshuizen^{2

3}, Dylan W de Lange^{4

5}, Wendy Beekman-Hendriks¹, Josien Lanfermeijer¹, Ferishta Bakhshi-Raiez^{4

6}, Dave A Dongelmans^{4

7}

Affiliations

¹ AstraZeneca BV, PO Box 93015, 2509 AA, Den Haag, The Netherlands.
² National Intensive Care Evaluation (NICE) Foundation, Postbus 23640, 1100 EC, Amsterdam, The Netherlands. f.termorshuizen@amsterdamumc.nl.
³ Amsterdam UMC, Department of Medical Informatics, University of Amsterdam, Amsterdam Public Health Research Institute, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. f.termorshuizen@amsterdamumc.nl.
⁴ National Intensive Care Evaluation (NICE) Foundation, Postbus 23640, 1100 EC, Amsterdam, The Netherlands.
⁵ Department of Intensive Care Medicine, University Medical Center, University of Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
⁶ Amsterdam UMC, Department of Medical Informatics, University of Amsterdam, Amsterdam Public Health Research Institute, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
⁷ Amsterdam UMC, Department of Intensive Care Medicine, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.

Abstract

Introduction: The corona virus disease 19 (COVID-19) pandemic has presented a global health challenge, and several consecutive variants of the severe acute respiratory syndrome-corona virus-2 (SARS-CoV-2) virus have been dominant. Previous studies highlighted decreased mortality rates during the predominance of the omicron variant; however, severely immunocompromised individuals remained at high risk due to limited vaccine response. This study aims to compare mortality rates during the omicron period between immunocompromised and non-immunocompromised patients in intensive care units (ICUs) in The Netherlands.

Methods: Utilizing data from the Dutch National Intensive Care Evaluation (NICE) registry, this study analyzed ICU admissions due to COVID-19 from February 2022 to December 2023. Patients were categorized as immunocompromised based on recorded immunologic insufficiencies or associated conditions. A historical cohort of viral pneumonia patients from 2017 to 2019 was used for comparison. Logistic regression analyses, adjusted for age, gender, body-mass index (BMI), and acute physiology and chronic health evaluation IV (APACHE-IV) mortality risk, compared in-hospital and ICU mortality and length of stay between groups. A sensitivity analysis excluded early omicron period admissions to assess the consistency of findings.

Results: Among 1491 patients admitted to the ICU due to COVID-19, 29.5% were immunocompromised, showing significantly higher in-hospital adjusted odds ratio (OR_adj = 1.56, 95% CI 1.20-2.04) and ICU mortality (OR_adj = 1.64, 95% CI 1.25-2.17) compared to non-immunocompromised patients. The historical cohort exhibited lower mortality rates for immunocompromised individuals compared to the COVID-19 cohort. Sensitivity analysis confirmed these trends, with slight attenuation of odds ratios.

Conclusion: Immunocompromised patients admitted to the ICU due to COVID-19 during the omicron period had higher mortality than non-immunocompromised patients. Additionally, immunocompromised patients with COVID-19 had higher mortality than immunocompromised patients with other viral pneumonias. Our results provide additional evidence that COVID-19 is still a significant health concern to immunocompromised individuals, which warrants specific and effective measures to protect this vulnerable group.

Keywords: COVID-19; ICU mortality; Immunocompromised patients; Omicron variant; SARS-CoV-2 virus.