University of Oulu

K. Miriam Elfström, Jonas Blomqvist, Peter Nilsson, Sophia Hober, Elisa Pin, Anna Månberg, Ville N. Pimenoff, Laila Sara Arroyo Mühr, Kalle Conneryd Lundgren, Joakim Dillner, Differences in risk for SARS-CoV-2 infection among healthcare workers, Preventive Medicine Reports, Volume 24, 2021, 101518, ISSN 2211-3355,

Differences in risk for SARS-CoV-2 infection among healthcare workers

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Author: Elfström, K. Miriam1; Blomqvist, Jonas1; Nilsson, Peter2;
Organizations: 1Karolinska University Hospital, Stockholm SE-141 86, Sweden
2Division of Affinity Proteomics, Department of Protein Science, KTH Royal Institute of Technology, SciLifeLab, Stockholm, Sweden
3Division of Protein Technology, Department of Protein Science, KTH Royal Institute of Technology, Stockholm, Sweden
4Karolinska Institute, Stockholm, Sweden
5University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.4 MB)
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Language: English
Published: Elsevier, 2021
Publish Date: 2021-11-17


Healthcare workers (HCWs) are a risk group for SARS-CoV-2 infection, but which healthcare work that conveys risk and to what extent such risk can be prevented is not clear. Starting on April 24th, 2020, all employees at work (n = 15,300) at the Karolinska University Hospital, Stockholm, Sweden were invited and 92% consented to participate in a SARS-CoV-2 cohort study. Complete SARS-CoV-2 serology was available for n = 12,928 employees and seroprevalences were analyzed by age, sex, profession, patient contact, and hospital department. Relative risks were estimated to examine the association between type of hospital department as a proxy for different working environment exposure and risk for seropositivity, adjusting for age, sex, sampling week, and profession. Wards that were primarily responsible for COVID-19 patients were at increased risk (adjusted OR 1.95 (95% CI 1.65–2.32) with the notable exception of the infectious diseases and intensive care units (adjusted OR 0.86 (95% CI 0.66–1.13)), that were not at increased risk despite being highly exposed. Several units with similar types of work varied greatly in seroprevalences. Among the professions examined, nurse assistants had the highest risk (adjusted OR 1.62 (95% CI 1.38–1.90)). Although healthcare workers, in particular nurse assistants, who attend to COVID-19 patients are a risk group for SARS-CoV-2 infection, several units caring for COVID-19 patients had no excess risk. Large variations in seroprevalences among similar units suggest that healthcare work-related risk of SARS-CoV-2 infection may be preventable.

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Series: Preventive medicine reports
ISSN: 2211-3355
ISSN-E: 2211-3355
ISSN-L: 2211-3355
Volume: 24
Article number: 101518
DOI: 10.1016/j.pmedr.2021.101518
Type of Publication: A1 Journal article – refereed
Field of Science: 3141 Health care science
Funding: Support was obtained from the Karolinska University Hospital, the County Council of Stockholm, Erling-Persson family foundation, KTH Royal Institute of Technology, Creades, and SciLifeLab. The funding agencies have had no role in the design, execution or interpretation of the study or in the decision to submit for publication.
Copyright information: © 2021 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (