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

• Published in: PloS one 2020-11, Vol.15 (11), p.e0240006-e0240006
• Main Authors: Brant-Zawadzki, Michael, Fridman, Deborah, Robinson, Philip A, Zahn, Matthew, Chau, Clayton, German, Randy, Breit, Marcus, Bock, Jason R, Hara, Junko
• Format: Article
• Language: English
• Subjects: Adult; Antibodies; Antibodies, Viral - analysis; Betacoronavirus; Biology and life sciences; California - epidemiology; Clinical Laboratory Techniques; Consent; Control; Coronavirus Infections - diagnosis; Coronavirus Infections - epidemiology; Coronaviruses; COVID-19; COVID-19 Testing; Disease transmission; Emergency medical care; Epidemics; Female; Fever; Health aspects; Health care; Health Personnel - statistics & numerical data; Health risks; Hospitals; Humans; Identification and classification; Immunoglobulin G; Infections; Laboratories; Lymphocytes; Lymphocytes T; Male; Medical personnel; Medical research; Medicine and Health Sciences; Middle Aged; Pandemics; People and Places; Pneumonia, Viral - epidemiology; Prevalence; Protective equipment; Questionnaires; SARS-CoV-2; Sensitivity analysis; Sensitivity and Specificity; Serological surveys; Severe acute respiratory syndrome; Severe acute respiratory syndrome coronavirus 2; Smell; Ultrasonic testing; United States; Viral diseases
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0240006

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.