One swab, two tests: Validation of dual SARS-CoV-2 testing on the Abbott ID NOW™

Abstract

Background Point-of-care tests (POCT) are promising tools to detect SARS-CoV-2 in specific settings. Initial reports suggest the ID NOW™ COVID-19 assay (Abbott Diagnostics Inc, USA) is less sensitive than standard real-time reverse transcription polymerase chain reaction (rRT-PCR) assays. This has raised concern over false negatives in SARS-CoV-2 POCT. Objectives We compared the performance of the ID NOW™ COVID-19 assay to our in-house rRT-PCR assay to assess whether dry swabs used in ID NOW™ testing could be stored in transport media and be re-tested by rRT-PCR for redundancy and to provide material for further investigation. Methods Paired respiratory swabs collected from patients at three acute care hospitals were used. One swab in transport media (McMaster Molecular Media (MMM)) was tested for SARS-CoV-2 by a laboratory-developed two-target rRT-PCR assay. The second was stored dry in a sterile container and tested by the ID NOW™ COVID-19 assay. Following ID NOW™ testing, dry swabs were stored in MMM for up to 48 hours and re-tested by rRT-PCR. Serially diluted SARS-CoV-2 particles were used to assess the impact of heat inactivation and storage time. Results Respiratory swabs (n=343) from 179 individuals were included. Using rRT-PCR results as the comparator, the ID NOW™ COVID-19 assay had positive (PPA) and negative (NPA) percent agreements of 87.0% (95% CI:0.74-0.94) and 99.7% (95% CI:0.98-0.99). Re-tested swabs placed in MMM following ID NOW testing had PPA and NPA of 88.8% (95% CI:0.76-0.95) and 99.7% (95% CI:0.98-0.99), respectively. Conclusions Storing spent dry swabs in transport media for redundancy rRT-PCR testing is a potential approach to address possible false negatives with the ID NOW™ COVID-19 assay.

Evaluating the Ability to ID (COVID-19) NOW: a Large Real-World Prospective Evaluation of the Abbott ID NOW COVID-19 Assay

“…( 8 , 9 , 11 , 12 ). Our study does, however, reflect similar results to performance characteristics of others ( 7 , 12 , 13 , 16 ). Diagnostic specificity (referred to as negative percent agreement in some studies) is reflective of these studies.…”

“…Although the ID NOW COVID-19 test is regarded as a rapid test (less than 15 min), it is not high throughput (one test per machine at one time) and requires rapid transportation times (within 1 h) that may not be plausible in large centers in normal settings. In addition, the “dry” swab may not be able to be used after testing, and so, downstream processing, such as whole genome sequencing, may not be possible unless an appropriate validation for the residual dry swab is done or a separate swab is collected ( 16 ). Any consideration for its application to alternative patient case uses such as outbreak settings or asymptomatic screening should be addressed with appropriate validation.…”

Diagnostic accuracy of the Abbott ID NOW SARS-CoV-2 rapid test for the triage of acute medical admissions

“…Results can be integrated automatically with hospital records which saves time and error by avoiding manual recording, and allows easy evaluation and audit. The reported performance of ID NOW in the literature to date has mostly come from small studies across a range of settings, with sensitivities ranging from 55-98% and specificities 95-100% when using RT-PCR as the gold standard [ 8 , [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] ]. Sensitivity approaches 100% when PCR results with a cycle threshold (Ct) value >30, suggesting a lower viral load, are excluded [ 15 , [19] , [20] , [21] ].…”