Severity of COVID-19 among Hospitalized Patients: Omicron Remains a Severe Threat for Immunocompromised Hosts
Louis Nevejan,
Sien Ombelet,
Lies Laenen,
Els Keyaerts,
Thomas Demuyser,
Lucie Seyler,
Oriane Soetens,
Els Van Nedervelde,
Reinout Naesens,
Dieter Geysels,
Walter Verstrepen,
Lien Cattoir,
Steven Martens,
Charlotte Michel,
Elise Mathieu,
Marijke Reynders,
Anton Evenepoel,
Jorn Hellemans,
Merijn Vanhee,
Koen Magerman,
Justine Maes,
Veerle Matheeussen,
Hélène Boogaerts,
Katrien Lagrou,
Lize Cuypers,
Emmanuel André
Affiliations
Louis Nevejan
Department of Laboratory Medicine, National Reference Center for Respiratory Pathogens, UZ Leuven—University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium
Sien Ombelet
Department of Laboratory Medicine, National Reference Center for Respiratory Pathogens, UZ Leuven—University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium
Lies Laenen
Department of Laboratory Medicine, National Reference Center for Respiratory Pathogens, UZ Leuven—University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium
Els Keyaerts
KU Leuven Department of Microbiology, Immunology and Transplantation, Laboratory of Clinical Microbiology, 3000 Leuven, Belgium
Thomas Demuyser
Department of Microbiology and Infection Control, Vrije Universiteit Brussel (VUB), UZ Brussel—University Hospitals Brussels, 1090 Brussels, Belgium
Lucie Seyler
Department of Internal Medicine and Infectious Diseases, Vrije Universiteit Brussel (VUB), UZ Brussel—University Hospitals Brussels, 1090 Brussels, Belgium
Oriane Soetens
Department of Microbiology and Infection Control, Vrije Universiteit Brussel (VUB), UZ Brussel—University Hospitals Brussels, 1090 Brussels, Belgium
Els Van Nedervelde
Department of Internal Medicine and Infectious Diseases, Vrije Universiteit Brussel (VUB), UZ Brussel—University Hospitals Brussels, 1090 Brussels, Belgium
Reinout Naesens
Department of Medical Microbiology, Department of infection prevention and control, ZNA Middelheim, 2020 Antwerp, Belgium
Dieter Geysels
Department of Medical Microbiology, Department of infection prevention and control, ZNA Middelheim, 2020 Antwerp, Belgium
Walter Verstrepen
Department of Medical Microbiology, Department of infection prevention and control, ZNA Middelheim, 2020 Antwerp, Belgium
Lien Cattoir
Clinical Laboratory of Microbiology, OLV Hospital, 9300 Aalst, Belgium
Steven Martens
Clinical Laboratory of Microbiology, OLV Hospital, 9300 Aalst, Belgium
Charlotte Michel
Department of Microbiology, Laboratoire Hospitalier Universitaire de Bruxelles, Université Libre de Bruxelles, 1000 Brussels, Belgium
Elise Mathieu
Department of Microbiology, Laboratoire Hospitalier Universitaire de Bruxelles, Université Libre de Bruxelles, 1000 Brussels, Belgium
Marijke Reynders
Department of Laboratory Medicine—Medical Microbiology, AZ Sint Jan Brugge-Oostende, 8000 Brugge, Belgium
Anton Evenepoel
Department of Laboratory Medicine—Medical Microbiology, AZ Sint Jan Brugge-Oostende, 8000 Brugge, Belgium
Jorn Hellemans
Department of Laboratory Medicine—Medical Microbiology, AZ Sint Jan Brugge-Oostende, 8000 Brugge, Belgium
Merijn Vanhee
Department of Laboratory Medicine—Medical Microbiology, AZ Sint Jan Brugge-Oostende, 8000 Brugge, Belgium
Department of Microbiology, University Hospital Antwerp, 2650 Antwerp, Belgium
Hélène Boogaerts
Department of Microbiology, University Hospital Antwerp, 2650 Antwerp, Belgium
Katrien Lagrou
Department of Laboratory Medicine, National Reference Center for Respiratory Pathogens, UZ Leuven—University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium
Lize Cuypers
Department of Laboratory Medicine, National Reference Center for Respiratory Pathogens, UZ Leuven—University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium
Emmanuel André
Department of Laboratory Medicine, National Reference Center for Respiratory Pathogens, UZ Leuven—University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium
The Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in the general population in the context of a relatively high immunity gained through the early waves of coronavirus disease 19 (COVID-19), and vaccination campaigns. Despite this context, a significant number of patients were hospitalized, and identifying the risk factors associated with severe disease in the Omicron era is critical for targeting further preventive, and curative interventions. We retrospectively analyzed the individual medical records of 1501 SARS-CoV-2 positive hospitalized patients between 13 December 2021, and 13 February 2022, in Belgium, of which 187 (12.5%) were infected with Delta, and 1036 (69.0%) with Omicron. Unvaccinated adults showed an increased risk of moderate/severe/critical/fatal COVID-19 (crude OR 1.54; 95% CI 1.09–2.16) compared to vaccinated patients, whether infected with Omicron or Delta. In adults infected with Omicron and moderate/severe/critical/fatal COVID-19 (n = 323), immunocompromised patients showed an increased risk of in-hospital mortality related to COVID-19 (adjusted OR 2.42; 95% CI 1.39–4.22), compared to non-immunocompromised patients. The upcoming impact of the pandemic will be defined by evolving viral variants, and the immune system status of the population. The observations support that, in the context of an intrinsically less virulent variant, vaccination and underlying patient immunity remain the main drivers of severe disease.