Clinical progression, disease severity, and mortality among adults hospitalized with COVID-19 caused by the Omicron and Delta SARS-CoV-2 variants: A population-based, matched cohort study

Zitta Barrella Harboe*, Casper Roed, Jon Gitz Holler, Fahim Iqbal Khan, Aya Nihad Abdulrahman Abdulrahman, Stefan Lundby Mulverstedt, Betina Lindgaard-Jensen, Barbara Bonnesen Bertelsen, Christian Søborg, Thyge Lynghøj Nielsen, Line Vinum Hansen, Birgitte Lindegaard Madsen, Andrea Browatzki, Mads Eiberg, Peter Haahr Bernhard, Emilie Marie Juelstorp Pedersen, Gertrud Baunbaek Egelund, Arnold Matovu Dungu, Adin Sejdic, Inger Hee Mabuza MathiesenNaja Z. Jespersen, Pelle Trier Petersen, Lars Nielsen, Micha Phill Grønholm Jepsen, Thomas Ingemann Pedersen, Robert Eriksson, Hans Eric Sebastian Seitz-Rasmussen, Morten Bestle, Henrik Andersen, Ulrik Skram, Mads Rømer Skøtt, Sarah Altaraihi, Pradeesh Sivapalan, Jens Ulrik Stæhr Jensen, Kristian Bagge, Kristina Melbardis Jørgensen, Maja Johanne Søndergaard Knudsen, Thomas Leineweber, Uffe Vest Schneider, Magnus Glindvad Ahlstrom, Sofie Rytter, Nina Le Dous, Pernille Ravn, Nanna Reiter, Daria Podlekareva, Andreas Knudsen, Stine Johnsen, Lars Erik Kristensen, Cæcilie Leding, Bastian Bryan Hertz, Thomas Benfield, Ole Kirk, Jon Gitz Holler, Sisse Rye Ostrowski, Sigurdur Thor Sigurdsson, Anders Perner, Nikolai Kirkby, Martin Schou Pedersen, Maarten Van Wijhe, Lone Simonsen, Peter Michael Bager, Tyra Grove Krause, Marianne Voldstedlund, Lasse Engbo Christiansen, Marc Stegger, Arieh Cohen, Jannik Fonager, Anders Fomsgaard, Rebecca Legarth, Morten Rasmussen, Sophie Gubbels, Jan Wohlfahrt, Troels Lillebæk, Caroline Klint Johannesen, Maarten Van Wijhe, Thea K. Fischer

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

14 Citations (Scopus)
17 Downloads (Pure)

Abstract

Background To compare the intrinsic virulence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) omicron variant with the delta variant in hospitalized adults with coronavirus disease 2019 (COVID-19). Methods All adults hospitalized in the Capital Region of Copenhagen with a positive reverse transcription polymerase chain reaction test for SARS-CoV-2 and an available variant determination from 1 September 2021 to 11 February 2022. Data from health registries and patient files were used. Omicron and Delta patients were matched (1:1) by age, sex, comorbidities, and vaccination status. We calculated crude and adjusted hazard ratios (aHRs) for severe hypoxemia and mortality at 30 and 60 days. Results 1,043 patients were included. Patients with Omicron were older, had more comorbidities, were frailer, and more often had three vaccine doses than those with Delta. Fewer patients with Omicron developed severe hypoxemia than those with Delta (aHR, 0.55; 95% confidence interval, 0.38 0.78). Omicron patients exhibited decreased aHR for 30- day mortality compared to Delta (aHR, 0.61; 0.39 0.95). Omicron patients who had received three vaccine doses had lower mortality compared to Delta patients who received three doses (aHR, 0.31;0.16 0.59), but not among those who received two or 0 1 doses (aHR, 0.86; 0.41 1.84 and 0.94; 0.49 1.81 respectively). Similar findings were observed for mortality at 60 days. Similar outcomes were obtained in the analyses of 316 individually matched patients. Conclusions Among adults hospitalized with COVID-19, those with Omicron had less severe hypoxemia and nearly 40% higher 30- and 60-day survival, as compared with those with Delta, mainly driven by a larger proportion of Omicron patients vaccinated with three doses of an mRNA vaccine.

Original languageEnglish
Article numbere0282806
JournalPLoS ONE
Volume18
Issue number4
Number of pages15
ISSN1932-6203
DOIs
Publication statusPublished - 2023

Bibliographical note

Publisher Copyright:
© 2023 COVID-19 Omicron Delta study group. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Cite this