One swab, two tests: validation of dual SARS-CoV-2 testing on the Abbott ID NOWâ„¢

Burnes, Laura E; Clark, Shawn T; Sheldrake, Elena; Faheem, Amna; Poon, Betty; Christie-Holmes, Natasha; Finlay, Laura; Kandel, Christopher; Phan, Michael; Frankland, Caylin; Lau, Trevor; Gubbay, Jonathan B; Corbeil, Antoine; Katz, Kevin; Kozak, Robert A.

BACKGROUND: Point-of-care tests (POCT) are promising tools to detect SARS-CoV-2 in specific settings. Initial reports suggest the ID NOWâ„¢ 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 NOWâ„¢ COVID-19 assay to our in-house rRT-PCR assay to assess whether dry swabs used in ID NOWâ„¢ 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 NOWâ„¢ COVID-19 assay. Following ID NOWâ„¢ 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 NOWâ„¢ 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 NOWâ„¢ COVID-19 assay.