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. 2021 Dec:145:105021.
doi: 10.1016/j.jcv.2021.105021. Epub 2021 Oct 30.

Prospective evaluation of ID NOW COVID-19 assay used as point-of-care test in an emergency department

Affiliations

Prospective evaluation of ID NOW COVID-19 assay used as point-of-care test in an emergency department

Jean-Claude NguyenVan et al. J Clin Virol. 2021 Dec.

Abstract

Background: Rapid testing for COVID-19 has been clearly identified as an essential component of the strategy to control the SARS-CoV-2 epidemic, worldwide. The ID NOW COVID-19 assay is a simple, user-friendly, rapid molecular biology test based on nicking and extension amplification reaction (NEAR).

Objectives: The aim of this study was to evaluate the ID NOW COVID-19 assay when used as a point-of-care test (POCT) in our Emergency Department (ED).

Type of study: This prospective study enrolled 395 consecutive patients; paired nasopharyngeal swabs were collected from each study participant. The first swab was tested with the ID NOW COVID-19 assay at the point-of-care by ED nurses. The second swab was diluted in viral transport medium (VTM) and sent to the clinical microbiology department for analysis by both the RT-PCR Simplexa test COVID-19 Direct assay as the study reference method, and the ID NOW COVID-19 assay performed in the laboratory.

Results: Nasopharyngeal swabs directly tested with the ID NOW COVID-19 assay yielded a sensitivity, specificity, PPV and NPV of 98.0%, 97.5%, 96.2% and 98.7%, respectively, in comparison with the RT-PCR study reference assay. When the ID NOW COVID-19 assay was performed in the laboratory using the VTM samples, the sensitivity decreased to 62.5% and the NPV to 79.7%. Three false negative test results were reported with the ID NOW COVID-19 assay when performed using undiluted swabs directly in the ED; these results were obtained from patients with elevated CT values (> 30).

Conclusion: We demonstrated that the ID NOW COVID-19 assay, performed as a point of care test in the ED using dry swabs, provides a rapid and reliable alternative to laboratory-based RT-PCR methods.

Keywords: COVID-19; Emergency department; ID NOW COVID-19; Isothermal amplification; Point-of-care test; SARS-CoV-2.

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Conflict of interest statement

We have no conflicts of interest to declare.

Figures

Fig 1
Fig. 1
Study flowchart. The arrow indicate the study flow, up to the final classification of 154 patients with the infection and without the infection.
Fig 2
Fig. 2
Comparison of CT values among positive samples detected by direct ID NOW COVID-19 assay and ID NOW COVID-19 assay performed on VTM. CT value differences were compared by using the Kruskal-Wallis test. VTM: viral transport medium.

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