Results of screening examination of employees of a medical hospital for antibodies to SARS-CoV-2

While providing medical care to patients with a new coronavirus infection, medical workers are at risk of developing COVID-19 significantly more often than the general population. In addition to morbidity risks, an important question is the duration of the immune response to COVID-19. The aim of our study is to assess the incidence of COVID-19 and the duration of the persistence of anti-SARS-CoV-2 antibodies among hospital medical staff. Material and methods. We conducted a retrospective non-randomized single-center study, based on the analysis of the laboratory database of the Municipal Clinical Hospital No. 52 (Moscow). The results of the 2160 employees were included into analysis. The inclusion criteria were as follows: at least one result of antibody determination to SARS-CoV-2 in period from June 2020 to January 2021;the date of the last antibody determination to SARS-CoV-2 no earlier than November 1, 2020. Additionally, a group of 100 employees were selected for further investigation of the persistence of immunoglobulin G (IgG) antibodies to SARS-CoV-2. Additionally, a group of 100 employees was selected, who had a confirmed fact of seroconversion for IgG and the presence of at least three results of IgG to SARS-CoV-2 determination with an interval of at least 4 weeks. Results. According to IgG determination results, by January 2021, 66.6% of all hospital employees have already been ill with COVID-19. The medical staff who worked with patients with COVID-19 been ill with COVID-19 in 78.2% of cases. The share of sick medical personnel who did not work with this group of patients was 55.3%. The first termination of antibodies persistence to SARS-CoV-2 from employees was marked from 3-4 months of observation. After 7-9 months, 23% of the observed group became seronegative. Odds ratio for the risk of COVID-19 for medical staff, who worked with COVID-19 patients was 2.89 (95% CI 2.34-3.56) to other medical staff and 3.6 (95% CI 2.82-4.59) to non-medical staff. Conclusion. The incidence of COVID-19 and the risk of infection among medical workers is significantly higher than among the general population, which dictates the need of further improvement of COVID-19 prevention measures among medical workers. © 2022 by the authors.