Dynamics of humoral response to coronavirus antigens among employees of a designated COVID‑19 hospital: an observational study.

Introduction: During the COVID‑19 pandemic studies on workplace safety of hospital staff taking care of patients with this disease are a high priority. We decided to analyze the results of opportunistic screening for anti-SARS‑CoV-2 antibodies among employees of a designated COVID-19 center.

Objectives: The aim of the study was to investigate whether potential exposition to SARS‑CoV-2 antigens is reflected in the results of serological studies.

Patients And Methods: Every employee who performed at least a single test between April 21 and July 20, 2020 was included in the study. The tests assessed the levels of immunoglobulin (Ig) G and IgM+IgA. Employees working in direct contact with COVID‑19 patients and those participating in aerosol‑generating procedures were identified.

Results: The results of 2455 tests taken by 1572 employees were analyzed. A total of 357 participants (22.7%) had at least 1 positive or equivocal result during the study period. Linear mixed models revealed gradual increases in mean levels of both IgG and IgM+IgA antibodies among employees with all negative results. The rate of change was higher among persons who had direct contact with COVID‑19 patients and the highest rate of change was observed among individuals participating in aerosol‑generating procedures.

Conclusions: We detected developing humoral immune response to a new set of coronavirus antigens among the study group. It is possible that employees of designated COVID‑19 centers are regularly exposed to noninfectious doses of SARS‑CoV-2 or its antigens.