Evaluation of an Electrochemiluminescent SARS-CoV-2 Antibody Assay

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Abstract

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 Cobas e801/e602 immunoassay analyzers.

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 715 coronavirus disease 2019 (COVID-19)-naive samples. We examined cross-reactivity against other antibody positive samples [syphilis, rheumatoid factor (RF), antinuclear antibody (ANA), double-stranded DNA (ds-DNA), influenza, dengue, hepatitis B (HBV), hepatitis C (HCV)] and the anti-SARS-CoV-2 kinetics.

Results

The assay cut-off index (COI) was linear up to 90.8. The interassay precision was 2.9% for a negative control (COI = 0.1) and 5.1% for a positive control (COI = 3.0). Assay time is 18 min and results are available 1 min later; throughput for 300 samples was 76 min. Only 1 case positive for HBsAg tested falsely positive; specificity was 99.9%. 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 patients 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 “seroconversion”) 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 seroconversion appears quite early.

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  1. SciScore for 10.1101/2020.06.28.20142232: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: As this work was part of routine evaluation of new diagnostic assays, it was deemed exempt by our institutional review board.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Antibody positive samples [dengue N=74, hepatitis C (HCV) N=3, hepatitis B (HBV) N=12, syphilis N=1, antinuclear antibody (ANA) N=16, double-stranded DNA antibody (anti-ds-DNA) N=4, rheumatoid factor (RF) N=7] were recruited for cross-reactivity analysis; these samples were from ambulatory subjects with no suspicion for COVID-19 or acute respiratory illness.
    antinuclear
    suggest…