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Performance of Abbott ID NOW COVID-19 rapid nucleic acid amplification test in nasopharyngeal swabs transported in viral media and dry nasal swabs, in a New York City academic institution

Our take —

Abbott ID NOW COVID-19 does not stand out compared to other platforms available for quickly identifying SARS-CoV-2 patients. With a high proportion of false negative tests compared to the Xpert Xpress, the sensitivity of Abbott ID NOW COVID-19 is not suitable for ruling out SARS-CoV-2 infection, however it might be useful in quickly identifying some infections particularly those with higher viral loads because it had a low false-negative rate. If used to rule-in infection, subsequent testing would need to be performed on samples with negative test results to confirm they are negative. Even though Abbott ID NOW COVID-19 provides a quicker way to test samples, the sensitivity is not suitable as a single rapid test, and/or should be validated by the user and be used in conjunction with other rapid testing.

Study design

Other

Study population and setting

Validation was conducted using serial dilutions of two known SARS-CoV-2 positive samples and previously confirmed and consecutive positive patients to assess testing sensitivity after collecting samples in viral transport medium, and using 101 paired nasopharyngeal (NP) samples in viral transport media (VTM) (for the Cepheid-Xpert-Xpress SARS-CoV-2) and dry swabs of nares and NP samples (Abbot ID NOW) obtained from patients in the ED with a doctor ordered COVID-19 test at New York University Langone Tisch Hospital . Samples were analyzed 1-2 hours after collection.

Summary of Main Findings

Using serial dilutions of samples stored in viral transport medium demonstrated a high positive test agreement on a sample with a high viral load but low positive agreement on a sample with a lower viral load – reflective of the viral loads seen in many positive cases at this medical center. Sensitivity of Abbott ID NOW COVID-19 for dry swabs of nares and NP was 51.6% and 66.7% of swabs with viral transport media, compared to Xpert Xpress platform.

Study Strengths

Strengths of this paper include comparison of platforms using both dry and VTM swabs as well as nares and NP samples. Each patient had multiple samples collected and validation was determined using various dilutions of samples.

Limitations

The Abbot ID NOW is intended to be a POC test and was not utilized in that manner although the researchers did follow the manufacturer’s recommendations for testing 1-2 hours after collection. The study was conducted using a small convenience sample of patients all seeking care at one hospital ED over the course of 3 days. The validation was conducted against a single platform (Xpert Xpress) therefore discrepancies between the two tests could not be resolved. All patients (except one) had reported to the ED with symptoms of COVID-19, therefore test performance on asymptomatic individuals is unknown

Value added

Although Abbott ID NOW COVID-19 provides results in a shorter amount of time (5-13 min) compared to other platforms, it is not as sensitive as Xpert Xpress and additional validation is required to better understand the sensitivity of this test.

This review was posted on: 4 July 2020