SARS-CoV-2 antibody prevalence in health care workers: Preliminary report of a single center study


SARS-CoV-2 has driven a pandemic crisis. Serological surveys have been conducted to establish prevalence for covid-19 antibody in various cohorts and communities. However, the prevalence among healthcare workers is still being analyzed. The present study reports on initial sero-surveillance conducted on healthcare workers at a regional hospital system in Orange County, California, during May and June, 2020. Study participants were recruited from the entire hospital employee workforce and the independent medical staff. Data were collected for job title, location, covid-19 symptoms, a PCR test history, travel record since January 2020, and existence of household contacts with covid-19. A blood sample was collected from each subject for serum analysis for IgG antibodies to SARS-CoV-2. Of 3,013 tested individuals, a total 2,932 were included in the analysis due to some missing data. Observed prevalence of 1.06% (31 antibody positive cases), adjusted prevalence of 1.13% for test sensitivity and specificity were identified. Significant group differences between positive vs. negative were observed for age (z = 2.65, p = .008), race (p = .037), presence of fever (p < .001) and loss of smell (p < .001). Possible explanation for this low prevalence includes a relatively low local geographic community prevalence (~4.4%) at the time of testing, the hospital's timely procurement of personal protective equipment, rigorous employee education, patient triage and treatment protocol development and implementation. In addition, possible greater presence of cross-reactive adaptive T cell mediated immunity in healthcare workers vs. the general population may have contributed. Determining antibody prevalence in front-line workers, and duration of antibody presence may help stratify the workforce for risk, establish better health place policies and procedures, and potentially better mitigate transmission.