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

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.

SARS-CoV-2 seroprevalence in healthcare workers at a frontline hospital in Tokyo

“…Similar to our data, several studies reported low seroprevalences among HCWs 19 – 21 . For example, in Greek where the prevalence of COVID-19 was only 0.12%, the overall seroprevalence in 1495 HCWs in two hospitals was 1.26% (95% CI 0.43, 3.26) 19 .…”

Prevalence and Longevity of SARS-CoV-2 Antibodies Among Health Care Workers

“…The present study found a considerably lower adjusted antibody prevalence (0.98%) on initial sampling (95.9% blood drawn during a “shelter at home” mandate in May–June 2020) among HCWs, confirming our initial findings [ 20 ] in a larger cohort. The community prevalence during this early period was relatively low (3.64%), as reflected by those tested by physician order in our community, and also reflected in adjusted prevalence among the first responders tested in this study (5.75%), though both these prevalence results were considerably higher than that of our HCWs.…”

“…Our previous study, conducted during a “shelter at home” mandate in May–June 2020, observed an antibody prevalence of 1.06% (adjusted antibody prevalence for test sensitivity and specificity of 1.13%) among our HCWs (n = 2924) at Hoag Memorial Hospital Presbyterian, Orange County, California. This was much lower than those reported by other studies [ 20 ]. Therefore, to further analyze the evolving prevalence of antibodies among HCWs, the present study expands our initial study in a larger HCW cohort and also reports on 8-week follow-up to investigate the longevity of antibody presence.…”

Serosurveillance of Health Care Workers in a COVID Hospital: Immune Response, and Its Longevity

“…Overall SARS-CoV-2 seroprevalence of 24.4% in HCWs was significantly greater than the 6% seroprevalence in the general population of the Midlands region, according to data published by Public Health England which suggests a marked occupational risk of exposure for HCWs during the COVID-19 pandemic [9]. Another study found 13.7% IgG prevalence among 40,329 HCWs in the greater New York City area similar to the community prevalence in New York State (14.0%) [15]. Hains et al [18] reported a seroconversion in 44.0% (n=11/25) of HCWs at a dialysis unit in America.…”

“…Variable seroreactivity has been reported in the literature, ranging from 57% prevalence in Bergamo-Italy's epicenter, 20% in New York City, 5.2% in Kenya, to a low percentage of 4.7% in Los Angeles County and 2.8% in Santa Clara County California [10,[14][15][16][17]. Overall SARS-CoV-2 seroprevalence of 24.4% in HCWs was significantly greater than the 6% seroprevalence in the general population of the Midlands region, according to data published by Public Health England which suggests a marked occupational risk of exposure for HCWs during the COVID-19 pandemic [9].…”