• William S Phipps, Jeffrey A SoRelle, Quan-Zhen Li, Lenin Mahimainathan, Ellen Araj, John Markantonis, Chantale Lacelle, Jyoti Balani, Hiren Parikh, E Blair Solow, David R Karp, Ravi Sarode, and Alagarraju Muthukumar.
• Department of Pathology, University of Texas Southwestern Medical Center, Dallas.
• Am. J. Clin. Pathol. 2020 Sep 8; 154 (4): 459-465.

ObjectivesInitial reports indicate adequate performance of some serology-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) assays. However, additional studies are required to facilitate interpretation of results, including how antibody levels impact immunity and disease course.MethodsA total of 967 subjects were tested for IgG antibodies reactive to SARS-CoV-2, including 172 suspected cases of SARS-CoV-2, 656 plasma samples from healthy donors, 49 sera from patients with rheumatic disease, and 90 specimens from individuals positive for polymerase chain reaction (PCR)-based respiratory viral panel. A subgroup of SARS-CoV-2 PCR-positive cases was tested for IgM antibodies by proteome array method.ResultsAll specificity and cross-reactivity specimens were negative for SARS-CoV-2 IgG antibodies (0/795, 0%). Positive agreement of IgG with PCR was 83% of samples confirmed to be more than 14 days from symptom onset, with less than 100% sensitivity attributable to a case with severe immunosuppression. Virus-specific IgM was positive in a higher proportion of cases less than 3 days from symptom onset. No association was observed between mild and severe disease course with respect to IgG and IgM levels.ConclusionsThe studied SARS-CoV-2 IgG assay had 100% specificity and no adverse cross-reactivity. Measures of IgG and IgM antibodies did not predict disease severity in our patient population.© American Society for Clinical Pathology, 2020.

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