Rapid Antigen Test Card and asymptomatic diagnosis

In a new wave of technology development, a rapid antigen test that reads results directly from a single card received emergency use authorization from the FDA this week. Unlike other diagnostic tests, BinaxNOW COVID-19 Ag Card does not require RT-PCR technology or a machine to read. To perform the test, a nasal swab specimen is collected from the patient and inserted into a well on a test card. Extraction reagent from a dropper bottle is added to the well and results can be interpreted visually at 15 minutes based on the presence or absence of pink/purple colored lines. Results can then be uploaded as an encrypted health message and accessed by the user through the free NAVICA app.

A recent study published in JAMA Internal Medicine found that the Ct values, which indicate viral load, in asymptomatic patients were similar to those in symptomatic patients (Lee et al. 2020). Although information regarding the infectiveness of asymptomatic individuals is yet to be clearly identified, asymptomatic persons seem to account for approximately 40% to 45% of SARS-CoV-2 infections based on current evidence and review (Oran and Topol 2020). The rapid antigen test is suggested for use within 7 days of symptom onset due to lower sensitivity compared to conventional RT-PCR nucleic-acid based tests (manufacturer reported sensitivity and specificity is 97.1% And 98.5%, respectively). However, because of the likelihood of asymptomatic spread, the CDC has provided recommendations for the use of antigen tests for asymptomatic individuals to meet the urgent need. Importantly, negative results should be considered presumptive and followed with RT-PCR if showing symptoms.

The manufacturer, Abbott, plans to make 50 million tests accessible monthly from the beginning of October at a cost of $5.00 per test.