ABSTRACT
BACKGROUND: Understanding severe acute respiratory syndrome coronavirus 2 antibody prevalence in a spectrum of health care workers (HCWs) may provide benchmarks of susceptibility, help us understand risk stratification, and support enactment of better health policies and procedures. METHODS: Blood serum was sampled at enrollment and 8-week follow-up from HCWs (nâ =â 3458) and from community first responders (nâ =â 226) for immunoglobulin G (IgG) analyses. Demographics, job duties, location, and coronavirus disease 2019-related information were collected. RESULTS: The observed IgG antibody prevalence was 0.93% and 2.58% at enrollment (May/June) and 8-week follow-up (July/August), respectively, for HCWs, and 5.31% and 4.35% for first responders. For HCWs, significant differences (Pâ <â .05) between negative and positive at initial assessment were found for age, race, fever, and loss of smell, and at 8-week follow-up for age, race, and all symptoms. Antibody positivity persisted at least 8 weeks in all positive HCWs. CONCLUSIONS: We found considerably lower antibody prevalence among HCWs compared with other published studies. While rigorous safety process measures instituted in our workplace and heightened awareness at and outside of the workplace among our HCWs may have contributed to our findings, the significant discrepancy from our community prevalence warrants further studies on other contributing factors.
ABSTRACT
Serological surveys have been conducted to establish prevalence for COVID-19 antibodies in various cohorts and communities, reporting a wide range of outcomes. The prevalence of such antibodies among healthcare workers, presumed at higher risk for infection, has been increasingly investigated, more studies are needed to better understand the risks and infection transmission in different healthcare settings. 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 subjects were recruited from the entire hospital employee workforce and the independent medical staff. Data were collected for job duties and locations, 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 2,992 tested individuals, a total 2,924 with complete data were included in the analysis. 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), but not for occupations (p = .710). 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, cross-reactive adaptive T cell mediated immunity, as recently described, may possibly play a greater role in healthcare workers than in the general population.