Initial determination of COVID-19 seroprevalence among outpatients and healthcare workers in Minnesota using a novel SARS-CoV-2 total antibody ELISA

Stefani N. Thomas, Ghaith Altawallbeh, Christopher P. Zaun, Kathryn A. Pape, Jennifer M. Peters, Philip J. Titcombe, Thamotharampillai Dileepan, Michael J. Rapp, Tyler D. Bold, Timothy W. Schacker, Sophie Arbefeville, Patricia Ferrieri, Bharat Thyagarajan, Marc K. Jenkins, Amy B. Karger

Research output: Contribution to journalArticlepeer-review

Abstract

Objectives: To avoid the significant risks posed by the use of COVID-19 serology tests with supply chain constraints or poor performance characteristics, we developed an in-house SARS-CoV-2 total antibody test. Our test was compared with three commercial methods, and was used to determine COVID-19 seroprevalence among healthcare workers and outpatients in Minnesota. Methods: Seventy-nine plasma and serum samples from 50 patients 4–69 days after symptom onset who tested positive by a SARS-CoV-2 PCR method using a nasopharyngeal (NP) swab were used to evaluate our test's clinical performance. Seropositive samples were analyzed for IgG titers in a follow-up assay. Thirty plasma and serum from 12 patients who tested negative by a SARS-CoV-2 PCR method using a nasopharyngeal (NP) swab and 210 negative pre-pandemic serum samples were also analyzed. Among samples from patients > 14 days after symptom onset, the assay had 100% clinical sensitivity and 100% clinical specificity, 100% positive predictive value and 100% negative predictive value. Analytical specificity was 99.8%, indicating minimal cross-reactivity. A screening study was conducted to ascertain COVID-19 seroprevalence among healthcare workers and outpatients in Minnesota. Results: Analysis of serum collected between April 13 and May 21, 2020 indicated a COVID-19 seroprevalence of 2.96% among 1,282 healthcare workers and 4.46% among 2,379 outpatients. Conclusions: Our in-house SARS-CoV-2 total antibody test can be used to conduct reliable epidemiological studies to inform public health decisions during the COVID-19 pandemic.

Original languageEnglish (US)
Pages (from-to)15-22
Number of pages8
JournalClinical Biochemistry
Volume90
DOIs
StatePublished - Apr 2021

Bibliographical note

Funding Information:
The authors gratefully acknowledge the following individuals for their contributions to this study: Dr. Fang Li (Professor, Department of Veterinary and Biomedical Sciences, University of Minnesota) for donating the RBD antigen used for the ELISA method; members of the labs of Drs. Marc Jenkins, Tyler Bold, Fang Li, and Bharat Thyagarajan; Steve J. Story (Technical Specialist, M Health Fairview Special Chemistry Laboratory), Christine K. Senn (Laboratory Manager, M Health Fairview University of Minnesota Medical Center West Bank Laboratory), Robert Janicek (Business Manager, University of Minnesota Advanced Research and Diagnostic Laboratory), Emily Kokaisel (Chemistry Technical Specialist, M Health Fairview University of Minnesota Medical Center East Bank Laboratory), Stephanie McGlone (Manager of Laboratory Services, M Health Fairview Bethesda and St. Joseph's Hospital), and the M Health Fairview COVID-19 System Command Center.

Publisher Copyright:
© 2021 The Canadian Society of Clinical Chemists

Keywords

  • Antibody
  • COVID-19
  • ELISA
  • SARS-CoV-2
  • Serology
  • Seroprevalence

PubMed: MeSH publication types

  • Journal Article

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