Objectives: Serological tests detect antibodies against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in the ongoing coronavirus disease-19 (COVID-19) pandemic . Independent external clinical validation of performance characteristics is of paramount importance .
Methods: Four fully automated assays, Roche Elecsys Anti-SARS-CoV-2, Abbott SARS-CoV-2 IgG, Siemens SARS-CoV-2 total (COV2T) and SARS-CoV-2 IgG (COV2G) were evaluated using 350 pre-pandemic samples and 700 samples from 245 COVID-19 patients (158 hospitalized, 87 outpatients).
Results: All tests showed very high diagnostic specificity . Sensitivities in samples collected at least 14 days after disease onset were slightly lower than manufacturers' claims for Roche (93.0 %), Abbott (90.8 %), and Siemens COV2T (90.3 %), and distinctly lower for Siemens COV2G (78.8 %). Concordantly negative results were enriched for immunocompromised patients . ROC curve analyses suggest a lowering of the cut-off index for the Siemens COV2G assay . Finally, the combination of two anti-SARS-CoV-2 antibody assays is feasible when considering borderline reactive results .
Conclusions: Thorough on-site evaluation of commercially available serologic tests for detection of antibodies against SARS-CoV-2 remains imperative for laboratories . The potentially impaired sensitivity of the Siemens COV2G necessitates a switch to the company's newly filed SARS-CoV-2 IgG assay for follow-up studies . A combination of tests could be considered in clinical practice.