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Initial Determination of COVID-19 Seroprevalence Among Outpatients and Healthcare Workers in Minnesota Using a Novel SARS-CoV-2 Total Antibody ELISA

32 Pages Posted: 25 Jun 2020

See all articles by Stefani N. Thomas

Stefani N. Thomas

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Ghaith Altawallbeh

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Christopher Zaun

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Kathryn Pape

Department of Microbiology and Immunology, Center for Immunology, School of Medicine, University of Minnesota

Jennifer M. Peters

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Philip J. Titcombe

Department of Medicine, Division of Rheumatology, Center for Immunology, School of Medicine, University of Minnesota

Thamotharampillai Dileepan

Department of Microbiology and Immunology, Center for Immunology, School of Medicine, University of Minnesota

Michael J. Rapp

M Health Fairview University of Minnesota Medical Center West BankLaboratory

Tyler D. Bold

Department of Medicine, Division of Infectious Diseases and International Medicine, 19School of Medicine, University of Minnesota

Timothy W. Schacker

University of Minnesota - Minneapolis

Sophie Arbefeville

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Patricia Ferrieri

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Bharat Thyagarajan

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Marc K. Jenkins

Department of Microbiology and Immunology, Center for Immunology, School of Medicine, University of Minnesota

Amy B. Karger

University of Minnesota - Minneapolis - Department of Laboratory Medicine and Pathology

More...

Abstract

Background: Antibody tests are critical in elucidating the epidemiology of the rapidly evolving Coronavirus Disease 2019 (COVID-19) global pandemic and in developing effective infection control measures. To avoid the significant risks posed by the use of tests with poor performance characteristics and associated supply chain disruptions, we developed an in-house SARS-CoV-2 total antibody test. The performance of our robustly validated test was compared with that of three commercial antibody tests, and our test was used to determine the seroprevalence of COVID-19 among healthcare workers and outpatients in Minnesota.  

Methods: To evaluate the clinical performance of our SARS-CoV-2 total antibody assay, 63 plasma and serum samples were analyzed from 34 SARS-CoV-2 PCR positive patients 4 - 35 days after symptom onset. Positive samples were analyzed for IgG titers in a follow up assay. Samples were analyzed from PCR negative (n=30) and presumed true negative pre-pandemic (n=207) patients. Among samples collected from patients >14 days after symptom onset, the assay had 100% diagnostic sensitivity (95% CI: 85·7 - 100·0%), 100% diagnostic specificity (95%CI: 98·5 - 100·0%), 100% positive predictive value (95% CI: 86·2 - 100·0%), and 100% negative predictive value (95%CI: 98·6 - 100·0%). The analytical specificity was 99·8% (95% CI: 98·92 - 99·97%), indicating minimal cross-reactivity. A screening study was conducted to ascertain the seroprevalence of COVID-19 among healthcare workers and outpatients in Minnesota.

Findings: Serum collected from 1,282 healthcare workers (1,000 females, 280 males, 2 gender unreported; median age 41 years [range 18 - 73]) and 2,379 outpatients (1,460 females, 916 males, 3 gender unreported; median age 49 years [range 2 months - 93 years]) between April 13 and May 21, 2020 was analyzed using our SARS-CoV-2 total antibody assay. The COVID-19 seroprevalence was 2·96% (95% CI: 2·04 - 3·89%) among healthcare workers and 4·46% (95% CI: 3·63 - 5·28%) among outpatients from 35 clinics who had a previous COVID-19 exposure or symptoms.

Interpretation: Rigorously validated serology tests with robust clinical and analytical performance, such as our in-house SARS-CoV-2 total antibody test, are of critical importance when conducting epidemiological studies to inform public health decisions during the COVID-19 pandemic.

Funding: University of Minnesota Department of Laboratory Medicine and Pathology

Declaration of Interests: The authors do not declare any competing interests.

Ethics Approval Statement: The University of Minnesota Institutional Review Board (IRB) determined that this study was not considered human research.

Note: Funding: None to declare

Suggested Citation

Thomas, Stefani N. and Altawallbeh, Ghaith and Zaun, Christopher and Pape, Kathryn and Peters, Jennifer M. and Titcombe, Philip J. and Dileepan, Thamotharampillai and Rapp, Michael J. and Bold, Tyler D. and Schacker, Timothy W. and Arbefeville, Sophie and Ferrieri, Patricia and Thyagarajan, Bharat and Jenkins, Marc K. and Karger, Amy B., Initial Determination of COVID-19 Seroprevalence Among Outpatients and Healthcare Workers in Minnesota Using a Novel SARS-CoV-2 Total Antibody ELISA (6/11/2020). Available at SSRN: https://ssrn.com/abstract=3627313 or http://dx.doi.org/10.2139/ssrn.3627313

Stefani N. Thomas

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Ghaith Altawallbeh

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Christopher Zaun

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Kathryn Pape

Department of Microbiology and Immunology, Center for Immunology, School of Medicine, University of Minnesota

Jennifer M. Peters

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Philip J. Titcombe

Department of Medicine, Division of Rheumatology, Center for Immunology, School of Medicine, University of Minnesota

Thamotharampillai Dileepan

Department of Microbiology and Immunology, Center for Immunology, School of Medicine, University of Minnesota

Michael J. Rapp

M Health Fairview University of Minnesota Medical Center West BankLaboratory

Tyler D. Bold

Department of Medicine, Division of Infectious Diseases and International Medicine, 19School of Medicine, University of Minnesota

Timothy W. Schacker

University of Minnesota - Minneapolis

110 Wulling Hall, 86 Pleasant St, S.E.
308 Harvard Street SE
Minneapolis, MN 55455
United States

Sophie Arbefeville

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Patricia Ferrieri

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Bharat Thyagarajan

Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota

Marc K. Jenkins

Department of Microbiology and Immunology, Center for Immunology, School of Medicine, University of Minnesota

Amy B. Karger (Contact Author)

University of Minnesota - Minneapolis - Department of Laboratory Medicine and Pathology ( email )

Minneapolis, MN
United States

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