Evaluation of Dried Blood Spot Testing for SARS-CoV-2 Serology Using a Quantitative Commercial Assay |
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| Authors: | Davor Brinc Mia J. Biondi Daniel Li Heng Sun Camelia Capraru David Smookler Muhammad Atif Zahoor Julia Casey Vathany Kulasingam Jordan J. Feld |
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| Affiliation: | 1.Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5S 1A8, Canada; (D.B.); (V.K.);2.Department of Clinical Biochemistry, University Health Network, Toronto, ON M5G 2C4, Canada;3.Viral Hepatitis Care Network (VIRCAN) Study Group, Toronto Centre for Liver Disease, Toronto, ON M5G 2C, Canada; (M.J.B.); (C.C.); (D.S.); (M.A.Z.); (J.C.);4.Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada; |
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| Abstract: | Dried blood spots (DBS) are commonly used for serologic testing for viruses and provide an alternative collection method when phlebotomy and/or conventional laboratory testing are not readily available. DBS collection could be used to facilitate widespread testing for SARS-CoV-2 antibodies to document past infection, vaccination, and potentially immunity. We investigated the characteristics of Roche’s Anti-SARS-CoV-2 (S) assay, a quantitative commercial assay for antibodies against the spike glycoprotein. Antibody levels were reduced relative to plasma following elution from DBS. Quantitative results from DBS samples were highly correlated with values from plasma (r2 = 0.98), allowing for extrapolation using DBS results to accurately estimate plasma antibody levels. High concordance between plasma and fingerpick DBS was observed in PCR-confirmed COVID-19 patients tested 90 days or more after the diagnosis (45/46 matched; 1/46 mismatched plasma vs. DBS). The assessment of antibody responses to SARS-CoV-2 using DBS may be feasible using a quantitative anti-S assay, although false negatives may rarely occur in those with very low antibody levels. |
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| Keywords: | SARS-CoV-2 COVID-19 dried blood spot serology antibody |
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