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

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

Lau CS, Hoo SP, Liang YL, Phua SK, Aw Tc

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. 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. 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). 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

antibodies, SARS-CoV-2, IgM, Assay evaluation

10.1016/j.plabm.2021.e00230

Practical laboratory medicine