SARS-CoV-2 infections among healthcare workers at Helsinki University Hospital, Finland, spring 2020: Serosurvey, symptoms and risk factors

Anu Kantele; Tinja Lääveri; Lauri Kareinen; Sari H Pakkanen; Karin Blomgren; Sointu Mero; Anu Patjas; Jenni Virtanen; Ruut Uusitalo; Maija Lappalainen; Asko Järvinen; Satu Kurkela; Anne J Jääskeläinen; Olli Vapalahti; Tarja Sironen

doi:10.1016/j.tmaid.2020.101949

SARS-CoV-2 infections among healthcare workers at Helsinki University Hospital, Finland, spring 2020: Serosurvey, symptoms and risk factors

Travel Med Infect Dis. 2021 Jan-Feb:39:101949. doi: 10.1016/j.tmaid.2020.101949. Epub 2020 Dec 13.

Authors

Affiliations

¹ Infectious Diseases, Inflammation Center, Helsinki University Hospital and University of Helsinki, Finland; Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Finland; Meilahti Vaccine Research Center, MeVac, Helsinki University Hospital and University of Helsinki, Finland. Electronic address: anu.kantele@hus.fi.
² Infectious Diseases, Inflammation Center, Helsinki University Hospital and University of Helsinki, Finland.
³ Department of Virology, Medicum, Faculty of Medicine, University of Helsinki, Finland; Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, 00014 University of Helsinki, Finland.
⁴ Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Finland; Meilahti Vaccine Research Center, MeVac, Helsinki University Hospital and University of Helsinki, Finland.
⁵ Meilahti Vaccine Research Center, MeVac, Helsinki University Hospital and University of Helsinki, Finland.
⁶ Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Finland.
⁷ Department of Virology, Medicum, Faculty of Medicine, University of Helsinki, Finland; Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, 00014 University of Helsinki, Finland; Department of Geosciences and Geography, Faculty of Science, University of Helsinki, Finland.
⁸ HUS Diagnostic Center, HUSLAB, Clinical Microbiology, University of Helsinki and Helsinki University Hospital, Finland.
⁹ Department of Virology, Medicum, Faculty of Medicine, University of Helsinki, Finland; Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, 00014 University of Helsinki, Finland; HUS Diagnostic Center, HUSLAB, Clinical Microbiology, University of Helsinki and Helsinki University Hospital, Finland.

Abstract

Background: Exposure, risks and immunity of healthcare workers (HCWs), a vital resource during the SARS-CoV-2 pandemic, warrant special attention.

Methods: HCWs at Helsinki University Hospital, Finland, filled in questionnaires and provided serum samples for SARS-CoV-2-specific antibody screening by Euroimmun IgG assay in March-April 2020. Positive/equivocal findings were confirmed by Abbott and microneutralization tests. Positivity by two of the three assays or RT-PCR indicated a Covid-19 case (CoV+).

Results: The rate of CoV(+) was 3.3% (36/1095) and seropositivity 3.0% (33/1095). CoV(+) was associated with contact with a known Covid-19 case, and working on a Covid-19-dedicated ward or one with cases among staff. The rate in the Covid-19-dedicated ICU was negligible. Smoking and age <55 years were associated with decreased risk. CoV(+) was strongly associated with ageusia, anosmia, myalgia, fatigue, fever, and chest pressure. Seropositivity was recorded for 89.3% of those with prior documented RT-PCR-positivity and 2.4% of those RT-PCR-negative. The rate of previously unidentified cases was 0.7% (8/1067) and asymptomatic ones 0% (0/36).

Conclusion: Undiagnosed and asymptomatic cases among HCWs proved rare. An increased risk was associated with Covid-19-dedicated wards. Particularly high rates were seen for wards with liberal HCW-HCW contacts, highlighting the importance of social distancing also among HCWs.

Keywords: Antibody response; Covid-19; HCW; Healthcare staff; Neutralizing antibodies; SARS-CoV-2.

MeSH terms

Adult
Antibodies, Viral / blood
Asymptomatic Infections / epidemiology
COVID-19 / diagnosis
COVID-19 / epidemiology*
COVID-19 / pathology
COVID-19 / prevention & control
Female
Finland / epidemiology
Health Personnel / statistics & numerical data*
Hospitals, University
Humans
Male
Middle Aged
Risk Factors
SARS-CoV-2 / immunology*
SARS-CoV-2 / isolation & purification
Seroepidemiologic Studies

Substances

Antibodies, Viral