Interlaboratory agreement of anti–severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serologic assays in the expedited College of American Pathologists proficiency testing program

Danyel H. Tacker, Christine Bashleben, Thomas C. Long, Elitza S. Theel, Vijaya Knight, Kamran Kadkhoda, Daniel D. Rhoads, Michael A. Linden, Susan L. Fink

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Context.—Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a recently emerged, currently pandemic virus, and the etiologic agent of coronavirus disease 2019 (COVID-19). Clinical testing for antibodies to SARS-CoV-2 has rapidly become widespread, but data regarding the interlaboratory performance of these serologic assays are limited. Objective.—To describe the development and initial results of the College of American Pathologists (CAP) SARS-CoV-2 Serology Survey. Design.—Members from the CAP Microbiology and Diagnostic Immunology and Flow Cytometry Committees formed a working group to support development of a new proficiency testing survey for anti–SARS-CoV-2 antibody assays. Supplemental questions in the survey assessed the state of SARS-CoV-2 serologic testing among participating laboratories as of July 2020. Results were analyzed for agreement by immunoglobulin (Ig) isotype tested, assay manufacturer, and methodology. Results.—A total of 4125 qualitative results were received from 1110 laboratories participating in the first survey. Qualitative agreement for assays measuring anti–SARS-CoV-2 total antibodies or IgG was greater than 90% for all 3 samples in the survey. Qualitative agreement for IgM and IgA for the negative sample was greater than 95%, but lacked consensus for the other 2 samples. Conclusions.—These initial data suggest overall excellent agreement and comparable performance for most qualitative anti–SARS-CoV-2 IgG and total antibody assays across all participating clinical laboratories, regardless of specific target antigen or assay methodology.

Original languageEnglish (US)
Pages (from-to)536-542
Number of pages7
JournalArchives of Pathology and Laboratory Medicine
Issue number5
StatePublished - May 1 2021

Bibliographical note

Funding Information:
Fink was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health under awards K08AI119142, R21AI130281, R21AI131269, and R21AI153487. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Theel reports participation on an advisory board for Roche Diagnostics, consulting for Accelerate Diagnostics and Siemens, and sponsored research funding from Roche Diagnostics and Ortho-Clinical Diagnostics. Rhoads performs sponsored research from IVD companies such as BD, Bio-Rad, and Roche, but he has received no funding for SARS-CoV-2 immunology studies. The other authors have no relevant financial interest in the products or companies described in this article.

Publisher Copyright:
© 2021 College of American Pathologists. All rights reserved.


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