Seroprevalence and Correlates of SARS-CoV-2 Antibodies in Health Care Workers in Chicago

John T. Wilkins, Elizabeth L. Gray, Amisha Wallia, Lisa R. Hirschhorn, Teresa R. Zembower, Joyce Ho, Naomi Kalume, Ojoma Agbo, Alex Zhu, Laura J. Rasmussen-Torvik, Sadiya S. Khan, Mercedes Carnethon, Mark Huffman, Charlesnika T. Evans

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19 Scopus citations


Background: Identifying factors associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among health care workers (HCWs) may help health systems optimize SARS-CoV-2 infection control strategies. Methods: We conducted a cross-sectional analysis of baseline data from the Northwestern HCW SARS-CoV-2 Serology Cohort Study. We used the Abbott Architect Nucleocapsid IgG assay to determine seropositivity. Logistic regression models (adjusted for demographics and self-reported community exposure to coronavirus disease 2019 [COVID-19]) were fit to quantify the associations between occupation group, health care delivery tasks, and community exposure and seropositive status. Results: A total of 6510 HCWs, including 1794 nurses and 904 non-patient-facing administrators, participated. The majority were women (79.6%), 74.9% were White, 9.7% were Asian, 7.3% were Hispanic, and 3.1% were non-Hispanic Black. The crude prevalence of seropositivity was 4.8% (95% CI, 4.6%-5.2%). Seropositivity varied by race/ethnicity as well as age, ranging from 4.2% to 9.6%. Out-of-hospital exposure to COVID-19 occurred in 9.3% of HCWs, 15.0% (95% CI, 12.2%-18.1%) of whom were seropositive; those with family members diagnosed with COVID-19 had a seropositivity rate of 54% (95% CI, 44.2%-65.2%). Support service workers (10.4%; 95% CI, 4.6%-19.4%), medical assistants (10.1%; 95% CI, 5.5%-16.6%), and nurses (7.6%; 95% CI, 6.4%-9.0%) had significantly higher seropositivity rates than administrators (referent; 3.3%; 95% CI, 2.3%-4.4%). However, after adjustment, nursing was the only occupation group with a significantly higher odds (odds ratio, 1.9; 95% CI, 1.3-2.9) of seropositivity. Exposure to patients receiving high-flow oxygen therapy and hemodialysis was significantly associated with 45% and 57% higher odds for seropositive status, respectively. Conclusions: HCWs are at risk for SARS-CoV-2 infection from longer-duration exposures to people infected with SARS-CoV-2 within health care settings and their communities of residence.

Original languageEnglish
Article numberofaa582
JournalOpen Forum Infectious Diseases
Issue number1
StatePublished - Jan 1 2021


  • COVID-19
  • health care workers
  • SARS-CoV-2
  • serology


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