Introduction: A year into the pandemic, the knowledge of SARS-CoV-2 infection risks among healthcare workers remains limited. In this cross-sectional study, we examined whether healthcare workers with high exposure to Covid-19 patients had a higher risk of SARS-CoV-2 infection than other healthcare workers in a Norwegian University Hospital. We also investigated the prevalence of asymptomatic healthcare workers in a ward with a SARS-CoV-2 outbreak.
Methods: Healthcare workers from five wards at Akershus University Hospital were included between May 11 and June 11, 2020. Blood samples were analyzed for SARS-CoV-2 antibodies and seroprevalences compared between participants with high and low exposure to Covid-19 patients. Demographic data and SARS-CoV-2 infection risk factors were recorded in a questionnaire. Naso-/oropharyngeal swabs from participants from the outbreak ward were analyzed by reverse transcriptase-polymerase chain reaction.
Results: 360/436 (82.6%) healthcare workers participated. 9/262 (3.4%) participants from wards with high exposure to Covid-19 patients were SARS-CoV-2 seropositive versus 3/98 (3.1%) from wards with low exposure (OR 1.13; 95%CI 0.3-4.26, p = .861). SARS-CoV-2 antibodies were found in 11/263 (4.2%) participants who had worked one or more shifts caring for Covid-19 patients versus in 1/85 (1.2%) without any known occupational Covid-19 exposure (OR 3.67; 95%CI 0.46-29.06, p = .187). SARS-CoV-2 was detected in naso-/oropharyngeal swabs from 2/78 (2.6%) participants.
Conclusion: We found no significantly increased risk of SARS-CoV-2 infection in healthcare workers with high exposure to COVID-19 patients. Five healthcare workers had either serologic or molecular evidence of past or present unrecognized SARS-CoV-2 infection.
Keywords: COVID-19; SARS-CoV-2; SARS-CoV-2 antibodies; asymptomatic; healthcare workers; transmission.