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. 2022 Sep;16(5):832-836.
doi: 10.1111/irv.12982. Epub 2022 Apr 13.

COVID-19 severity from Omicron and Delta SARS-CoV-2 variants

Jesse O Wrenn  1 , Suman B Pakala  2 , Grant Vestal  2 , Meghan H Shilts  2 , Hunter M Brown  2 , Sara M Bowen  3 , Britton A Strickland  3 , Timothy Williams  3 , Simon A Mallal  2 , Ian D Jones  1 , Jonathan E Schmitz  3 , Wesley H Self  1 , Suman R Das  2   3   4
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COVID-19 severity from Omicron and Delta SARS-CoV-2 variants

Jesse O Wrenn et al. Influenza Other Respir Viruses. 2022 Sep.

Abstract

The Omicron variant of SARS-CoV-2 achieved worldwide dominance in late 2021. Early work suggests that infections caused by the Omicron variant may be less severe than those caused by the Delta variant. We sought to compare clinical outcomes of infections caused by these two strains, confirmed by whole genome sequencing, over a short period of time, from respiratory samples collected from SARS-CoV-2 positive patients at a large medical center. We found that infections caused by the Omicron variant caused significantly less morbidity, including admission to the hospital and requirement for oxygen supplementation, and significantly less mortality than those caused by the Delta variant.

Keywords: COVID-19; Delta; Omicron; SARS-CoV-2; severity; whole genome sequencing (WGS).

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Conflict of interest statement

All authors declare no conflict of interest to share.

Figures

FIGURE 1
FIGURE 1
The Delta variant was associated with more severe COVID‐19 than the Omicron variant. (A) The highest severity level experienced on the WHO COVID‐19 Clinical Progression Scale among all patients included in the study, documented in the medical record within 14 days of positive test or during admission initiating within 14 days of positive test, is graphed for patients with Omicron (n = 263) vs. Delta (n = 489) infection. (B) The highest severity level experienced on the WHO COVID‐19 Clinical Progression Scale is shown for only admitted patients with Omicron (n = 14) vs. Delta (n = 64) infection. Among patients with Omicron infection, there was no mortality or mechanical ventilation
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