COVID-19 exposure in SARS-CoV-2-seropositive hospital staff members during the first pandemic wave at Strasbourg University Hospital, France

OBJECTIVES: Strasbourg University Hospital faced an important COVID-19 first wave from early March 2020. We performed a longitudinal prospective cohort study to describe clinical and virological data, exposure history to COVID-19, and adherence to strict hygiene standards during the first pandemic wave in 1497 workers undergoing a SARS-CoV-2 serological test at our hospital, with a follow up of serology result three months later. PATIENTS AND METHODS: A total of 1497 patients were enrolled from April 6 to May 7, 2020. Antibody response to SARS-CoV-2 was measured, and COVID-19 exposure routes were analyzed according to SARS-CoV-2 serological status. RESULTS: A total of 515 patients (34.4%) were seropositive, mainly medical students (13.2%) and assistant nurses (12.0%). A history of COVID-19 exposure in a professional and/or private setting was mentioned by 83.1% of seropositive subjects (P < 0.05; odds ratio [OR]: 2.5; 95% confidence interval [CI]: 1.8–3.4). COVID-19 exposure factors associated with seropositive status were non-professional exposure (OR: 1.9, 95% CI: 1.3–2.7), especially outside the immediate family circle (OR: 2.2, 95% CI: 1.2–3.9) and contact with a COVID-19 patient (OR: 1.6; 95% CI: 1.1–2.2). Among professionally exposed workers, systematic adherence to strict hygiene standards was well observed, except for the use of a surgical mask (P < 0.05, OR: 1.9, 95% CI: 1.3–2.8). Of those who reported occasionally or never wearing a surgical mask, nurses (25.7%), assistant nurses (16.2%), and medical students (11.7%) were predominant. CONCLUSION: Infection of staff members during the first pandemic wave in our hospital occurred after both professional and private COVID-19 exposure, underlining the importance of continuous training in strict hygiene standards.