Side-by-Side Comparison of Three Fully Automated SARS-CoV-2 Antibody Assays with a Focus on Specificity

Background In the context of the COVID-19 pandemic, numerous new serological test systems for the detection of anti-SARS-CoV-2 antibodies rapidly have become available. However, the clinical performance of many of these is still insufficiently described. Therefore, we compared 3 commercial CE-marked, SARS-CoV-2 antibody assays side by side. Methods We included a total of 1154 specimens from pre-COVID-19 times and 65 samples from COVID-19 patients (≥14 days after symptom onset) to evaluate the test performance of SARS-CoV-2 serological assays by Abbott, Roche, and DiaSorin. Results All 3 assays presented with high specificities: 99.2% (98.6–99.7) for Abbott, 99.7% (99.2–100.0) for Roche, and 98.3% (97.3–98.9) for DiaSorin. In contrast to the manufacturers’ specifications, sensitivities only ranged from 83.1% to 89.2%. Although the 3 methods were in good agreement (Cohen’s Kappa 0.71–0.87), McNemar tests revealed significant differences between results obtained from Roche and DiaSorin. However, at low seroprevalences, the minor differences in specificity resulted in profound discrepancies of positive predictive values at 1% seroprevalence: 52.3% (36.2–67.9), 77.6% (52.8–91.5), and 32.6% (23.6–43.1) for Abbott, Roche, and DiaSorin, respectively. Conclusion We found diagnostically relevant differences in specificities for the anti-SARS-CoV-2 antibody assays by Abbott, Roche, and DiaSorin that have a significant impact on the positive predictive values of these tests.