Performance Characteristics of a Rapid Severe Acute Respiratory Syndrome Coronavirus 2 Antigen Detection Assay at a Public Plaza Testing Site in San Francisco

  1. Genay Pilarowski
  2. Paul Lebel
  3. Sara Sunshine
  4. Jamin Liu
  5. Emily Crawford
  6. Carina Marquez
  7. Luis Rubio
  8. Gabriel Chamie
  9. Jackie Martinez
  10. James Peng
  11. Douglas Black
  12. Wesley Wu
  13. John Pak
  14. Matthew T Laurie
  15. Diane Jones
  16. Steve Miller
  17. Jon Jacobo
  18. Susana Rojas
  19. Susy Rojas
  20. Robert Nakamura
  21. Valerie Tulier-Laiwa
  22. Maya Petersen
  23. Diane V Havlir
  24. Joseph DeRisi

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Abstract

We evaluated the performance of the Abbott BinaxNOW rapid antigen test for coronavirus disease 2019 (Binax-CoV2) to detect virus among persons, regardless of symptoms, at a public plaza site of ongoing community transmission. Titration with cultured severe acute respiratory syndrome coronavirus 2 yielded a human observable threshold between 1.6 × 104-4.3 × 104 viral RNA copies (cycle threshold [Ct], 30.3–28.8). Among 878 subjects tested, 3% (26 of 878) were positive by reverse-transcription polymerase chain reaction, of whom 15 of 26 had a Ct <30, indicating high viral load; of these, 40% (6 of 15) were asymptomatic. Using this Ct threshold (<30) for Binax-CoV2 evaluation, the sensitivity of Binax-CoV2 was 93.3% (95% confidence interval, 68.1%–99.8%) (14 of 15) and the specificity was 99.9% (99.4%–99.9%) (855 of 856).

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  1. ScreenIT

    SciScore for 10.1101/2020.11.02.20223891: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: Ethics statement: The UCSF Committee on Human Research determined that the study met criteria for public health surveillance.
    Consent: All participants provided informed consent for dual testing.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Experimental Models: Cell Lines
    SentencesResources
    Titration of in vitro cultured SARS-CoV-2 on Binax-CoV2 cards: SARS-CoV-2 from a UCSF clinical specimen was isolated, propagated and plaqued on Huh7.5.1 cells overexpressing ACE2 and TMPRSS2 [12].
    Huh7.5.1
    suggested: RRID:CVCL_E049)
    Software and Algorithms
    SentencesResources
    Field Testing using Binax-CoV2 assay: Binax-CoV2 assay was performed by technicians on site as described by the manufacturer using the supplied Puritan swabs.
    Field Testing
    suggested: None

    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:
    Limitations of our study include its cross-sectional design and overall small number of RT-PCR positive cases. Additional field performance of this assay is needed and will help inform optimal use strategies. We recommend evaluating the Binax-CoV2 assay side by side with RT-PCR in each context it will be used prior to use of Binax-CoV2 without the use of RT-PCR. During the early stages of infection, viral load may be too low to detect by direct antigen assays, such as Binax-CoV2. This inherent lower sensitivity may be offset by faster turn-around, the ability to test more frequently, and overall lower cost, relative to traditional RT-PCR methods. That said, for persons who present with a high index of suspicion of COVID-19 and a negative Binax-CoV2 result, the test should be complimented with RT-PCR or a repeat Binax-CoV2 test at a later time to make sure case not missed. In summary, under field conditions with supplementary technician training, the Binax-CoV2 assay accurately detected SARS-CoV-2 infection with high viral loads in both asymptomatic and symptomatic individuals. The Binax-CoV2 test could be a valuable asset in an arsenal of testing tools for the mitigation of SARS-CoV-2 spread, as rapid identification of highly infectious individuals is critical.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).

    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.

  2. Version published to 10.1093/infdis/jiaa802
  3. Version published to 10.1101/2020.11.02.20223891v2 on medRxiv
  4. Version published to 10.1101/2020.11.02.20223891v1 on medRxiv