Avoiding False-Positive SARS-CoV-2 Rapid Antigen Test Results with Point-of-Care Molecular Testing on Residual Test...

Area of Science:

• Virology
• Infectious Diseases
• Diagnostic Technologies

Background:

• Antigen-based rapid diagnostic tests (Ag-RDTs) are widely used for SARS-CoV-2 detection.
• Confirmation with nucleic acid amplification tests (NAATs) is recommended for positive Ag-RDTs in low-prevalence settings.
• Current confirmation protocols often necessitate repeat specimen collection and laboratory testing, causing delays.

Purpose of the Study:

• To evaluate the utility of a point-of-care molecular NAAT (ID NOW) for SARS-CoV-2 detection.
• To assess the performance of ID NOW using residual test buffer (RTB) from positive Ag-RDTs.
• To determine if on-site testing can obviate the need for specimen recollection for confirmatory molecular testing.

Main Methods:

• A point-of-care molecular NAAT (ID NOW) was performed on RTB from positive Abbott Panbio and BTNX Rapid Response Ag-RDTs.
• Results from ID NOW testing of RTB were compared to real-time RT-PCR performed at a reference laboratory.
• Analytical specificity was assessed using a panel of various respiratory organisms.

Main Results:

• ID NOW accurately identified all 354 true-positive Ag-RDT results confirmed by RT-PCR.
• No SARS-CoV-2 was detected by ID NOW from 10 false-positive Ag-RDT specimens.
• No SARS-CoV-2 was detected from contrived specimens containing various respiratory organisms, indicating high specificity.

Conclusions:

• On-site molecular testing of RTB from positive Ag-RDTs is a viable strategy for rapid confirmation.
• This approach eliminates the need for patient recall and specimen recollection for molecular testing.
• The method enhances diagnostic efficiency and turnaround time for SARS-CoV-2 confirmation.