Evaluation of an Electrochemiluminescent SARS-CoV-2 Antibody Assay

  1. C S Lau
  2. S P Hoo
  3. S F Yew
  4. S K Ong
  5. L T Lum
  6. P Y Heng
  7. J G Tan
  8. M S Wong
  9. T C Aw

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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. Version published to 10.1093/jalm/jfaa134
  2. ScreenIT

    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
    suggested: (MyBioSource Cat# MBS720508, RRID:AB_10891162)
    anti-ds-DNA
    suggested: None
    Software and Algorithms
    SentencesResources
    Statistical analyses were performed using MedCalc software v19.3.1 (MedCalc, Ostend, Belgium).
    MedCalc
    suggested: (MedCalc, RRID:SCR_015044)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    A limitation of our study is that we have relatively fewer samples for cases after 14 days POS. Further studies on larger populations would be desirable. In addition, we do not have the sero-prevalence of SARS-CoV-2 in our community. At the time of this study, we created our own negative and positive control materials from patient sera based on manufacturer recommendations. However, control materials have since been supplied by the manufacturer. The on-board reagent stability of 72 hours in the initial manufacturer information sheet has also been updated to 14 days.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2020.06.28.20142232v1 on medRxiv