Specific exposure of ICU staff to SARS-CoV-2 seropositivity: a wide seroprevalence study in a French city-center hospital.

Background: Most hospital organizations have had to face the burden of managing the ongoing COVID-19 outbreak. One of the challenges in overcoming the influx of COVID-19 patients is controlling patient-to-staff transmission. Measuring the specific extent of ICU caregiver exposure to the virus and identifying the associated risk factors are, therefore, critical issues. We prospectively studied SARS-CoV-2 seroprevalence in the staff of a hospital in Lyon, France, several weeks after a first epidemic wave. Risk factors for the presence of SARS-CoV-2 antibodies were identified using a questionnaire survey.

Results: The overall seroprevalence was 9% (87/971 subjects). Greater exposure was associated with higher seroprevalence, with a rate of 3.2% [95% CI 1.1-5.2%] among non-healthcare staff, 11.3% [8.9-13.7%] among all healthcare staff, and 16.3% [12.3-20.2%] among healthcare staff in COVID-19 units. The seroprevalence was dramatically lower (3.7% [1.0-6.7%]) in the COVID-19 ICU. Risk factors for seropositivity were contact with a COVID-19-confirmed household (odds ratio (OR), 3.7 [1.8-7.4]), working in a COVID-19 unit (OR, 3.5 [2.2-5.7], and contact with a confirmed COVID-19 coworker (OR, 1.9 [1.2-3.1]). Conversely, working in the COVID-19-ICU was negatively associated with seropositivity (OR, 0.33 [0.15-0.73]).

Conclusions: In this hospital, SARS-CoV-2 seroprevalence was higher among staff than in the general population. Seropositivity rates were particularly high for staff in contact with COVID-19 patients, especially those in the emergency department and in the COVID-19 unit, but were much lower in ICU staff. Clinical trial registration NCT04422977.