Clinical Validity of Serum Antibodies to SARS-CoV-2
Giorgio Caturegli, Joshua Materi, Brittney M. Howard, Patrizio Caturegli
Abstract
BACKGROUND: The clinical utility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies remains undefined. OBJECTIVE: To determine the clinical validity and utility of SARS-CoV-2 antibodies. DESIGN: Case-control study. SETTING: First month of testing for coronavirus disease 2019 (COVID-19) by using a nucleic acid amplification test (NAAT) on nasopharyngeal swabs at the Johns Hopkins Hospital, Baltimore, Maryland (11 066 persons). PARTICIPANTS: = 55). The laboratory control groups comprised 513 persons not tested by NAAT: 160 healthy laboratory employees, 101 persons positive for IgG antibodies against Epstein-Barr virus capsid antigen, 215 positive for thyroperoxidase antibody, and 37 positive for rheumatoid factor. MEASUREMENTS: Serum IgG and IgA antibodies against SARS-CoV-2 spike protein were detected by using enzyme-linked immunosorbent assay. RESULTS: = 0.001). LIMITATIONS: The study was retrospective and performed at a single center; the sample was small; follow-up was limited; and selection bias may have occurred. CONCLUSION: Antibodies to SARS-CoV-2 demonstrate infection when measured at least 14 days after symptom onset, are associated with clinical severity, and provide valuable diagnostic support in patients who test negative by NAAT but remain clinically suspicious for COVID-19. PRIMARY FUNDING SOURCE: Clinical Immunology Laboratory, Department of Pathology, Johns Hopkins Hospital.