EVALUATION OF THE ROCHE ELECSYS ANTI-SARS-COV-2 ASSAY.

Lau, C.; Hoo, S.; Yew, S.; Ong, S.; Lum, L.; Heng, P.; Tan, J.; Wong, M.; Aw, T.

Background: Little is known about the performance of the Roche novel severe acute respiratory syndrome coronavirus 2 antibody (anti-SARS-CoV-2) assay. We provide an extensive evaluation of this fully automated assay on the Cobas e801/e602 immunoassay analysers. Methods: We assessed the linearity, precision, and throughput of the Roche anti-SARS-CoV-2 assay. Sensitivity was calculated from 349 SARS-CoV-2 polymerase chain reaction (PCR) positive samples; specificity was determined from 714 coronavirus disease 2019 (COVID-19)-naive samples. We examined cross-reactivity against other antibody positive samples (syphilis, RF, ANA, ds-DNA, influenza, dengue, HBV, HCV) and the anti-SARS-CoV-2 kinetics. Results: The assay cut-off index (COI) was linear up to 90.7. The inter-assay precision was 2.9% for a negative control (COI=0.1) and 5.1% for a positive control (COI=3.0). Assay time is 18min and results are available 1 minute later; throughput for 300 samples was 76 minutes. No cross-reactivity was observed with other antibody positive samples; specificity was 100%. The assay has a sensitivity of 97.1% 14 days after PCR positivity (POS) and 100% at [≥]21 days POS; 48.2% of cases had anti-SARS-CoV-2 within 6 days POS. In 11 subjects in whom serum was available prior to a positive antibody signal (COI [≥]1.0) the interval between the last negative and first positive COI (time to sero-conversion) on average is 3 days (range 1-6 days) and 4 more days (range 1-7) for the anti-SARS-CoV-2 to plateau. Conclusion: The Roche anti-SARS-CoV-2 assay shows excellent performance with minimal cross-reactivity from other viral and confounding antibodies. Antibody development and sero-conversion appears quite early.