A comparison of severity of illness between the SARS-CoV-2 Omicron variant and Delta variant

Laura Peyton Ellis; Olivia Hess; Khoa Le Anh Huynh; Gonzalo Bearman; Le Kang; Christopher D Doern

doi:10.1017/ash.2023.453

A comparison of severity of illness between the SARS-CoV-2 Omicron variant and Delta variant

Antimicrob Steward Healthc Epidemiol. 2023 Oct 27;3(1):e188. doi: 10.1017/ash.2023.453. eCollection 2023.

Authors

Laura Peyton Ellis^#¹, Olivia Hess^#², Khoa Le Anh Huynh³, Gonzalo Bearman^{4

5}, Le Kang³, Christopher D Doern⁶

Affiliations

¹ Obstetrics and Gynecology Residency Program, University of Connecticut, Farmington, CT, USA.
² School of Medicine, Virginia Commonwealth University, Richmond, VA, USA.
³ Department of Biostatistics, Virginia Commonwealth University, Richmond, VA, USA.
⁴ Richard P. Wenzel Professor of Medicine, Chair, Division of Infectious Diseases, Virginia Commonwealth University, Richmond, VA, USA.
⁵ Antimicrobial Stewardship and Healthcare Epidemiology, Cambridge University Press, Cambridge, UK.
⁶ Microbiology & Pathology and Pediatrics, Virginia Commonwealth University, Richmond, VA, USA.

^# Contributed equally.

Abstract

Background: The COVID-19 pandemic has disproportionally affected traditionally marginalized groups. Both the Delta and Omicron variants raised concern amongst public health officials due to potentially higher infectivity rates and disease severity than prior variants. This study sought to compare disease severity between adults infected with the Omicron variant and adults infected with the Delta variant who presented to the Emergency Department at an academic, safety-net hospital in Virginia.

Methods: This retrospective cohort study used electronic medical record data of patients who presented to the Emergency Department and received a positive SARS-CoV-2 test between September 1, 2021, and January 31, 2022. Positive tests were stratified by genotypic variant through whole genome sequencing. Participants with the Omicron variant were propensity scores matched with individuals with the Delta variant.

Results: Among 500 Delta and 500 Omicron participants, 279 propensity score-matched pairs were identified. Participants were predominantly unvaccinated, with medical comorbidities, and self-identified as Black. Individuals infected with the Delta variant had more severe disease compared to those with the Omicron variant, regardless of vaccination status. Patients with kidney, liver, and respiratory disease, as well as cancer, are at higher risk for severe disease. Patients with 2 doses of COVID-19 immunization trended toward less severe disease.

Conclusions: Overall, these data further support the literature regarding the disproportionate effects of the COVID-19 pandemic on vulnerable patient populations - such as those with limited access to care, people of color, and those with chronic medical conditions - and can be used to inform public health interventions.