Performance of an automated chemiluminescent immunoassay for SARS-COV-2 IgM and head-to-head comparison of Abbott and Roche COVID-19 antibody assays

• Main Authors: CS, L. (Author), SK, P. (Author), SP, H. (Author), TC, A. (Author), YL, L. (Author)
• Format: Article
• Language: English
• Published: Elsevier B.V. 2021
• Subjects: adult; aged; Antibodies; antibody detection; Article; Assay evaluation; automation; chemiluminescence immunoassay; clinical article; controlled study; coronavirus disease 2019; COVID 19 antibody assay; cross reaction; diagnostic accuracy; diagnostic test accuracy study; double stranded DNA; female; human; IgM; immunoassay; immunoglobulin G; immunoglobulin M; intermethod comparison; male; nonhuman; reverse transcription polymerase chain reaction; SARS-CoV-2; sensitivity and specificity; seroconversion; Severe acute respiratory syndrome coronavirus 2; virus detection
• Online Access: View Fulltext in Publisher

 Introduction: We evaluated the performance of the new Abbott SARS-CoV-2 IgM assay on the Architect immunoassay analyser and compared it to the Architect IgG/Roche Cobas total antibody assays in both SARS-CoV-2 RT-PCR positive cases and healthy controls. Method: 200 healthy control samples and 48 individuals with other antibody-positive disorders (18 hepatitis/18 dengue/11 ANA/1 dsDNA) served to assess for potential cross-reactivity. Anonymised residual leftover sera positive for SARS-CoV-2 on RT-PCR were recruited as cases (N ​= ​133). The sensitivity/specificity/cross-reactivity of the Architect IgM assay were assessed. Concordance between the 3 assays were also analysed. Results: There was no cross-reactivity with controls and other antibody positive samples. The Architect IgM assay was 100% specific (95% CI 98.5 to 100) and sensitivity was 77.8% (95% CI 60.8 to 89.9) ≥14 days post-first positive RT-PCR (POS). Sensitivity of the combined Architect IgM and IgG results (30.8%) was significantly better than the Cobas total antibodies (15.4%) in early disease (p ​= ​0.04). While the Architect IgM assay had moderate agreement with the Cobas total antibody result (Cohen's kappa 0.72), a combined Architect IgM and IgG result had better agreement (Cohen's kappa 0.83). Conclusion: The Architect IgM assay has good specificity and no cross-reactivity with other antibody positive cases. A combined Architect IgM and IgG result has better sensitivity than the individual assays for early COVID-19. The Architect IgM assay is not comparable to the Cobas total antibody assay, but the Architect IgM and IgG combined result has good agreement with the Cobas assay. © 2021 The Authors