How reliably can a rapid COVID-19 antigen test detect infection in people with mild symptoms or no symptoms?

Details

Molecular tests are the gold standard for diagnosing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, but they involve a diagnostic delay. Antigen detection tests can provide results within 20 minutes, even outside a laboratory.

To evaluate the accuracy and reliability of the FAST COVID-19 SARS-CoV-2 Antigen Rapid Test Kit (Ag-RDT), researchers conducted a paired-sample diagnostic performance study. Two respiratory swabs were collected simultaneously from each of 501 patients with mild or no coronavirus disease 2019 (COVID-19)-related symptoms. Samples were analyzed using both Reverse Transcriptase-quantitative Polymerase Chain Reaction (RT-qPCR) and the FAST COVID-19 SARS-CoV-2 Antigen Rapid Test. The results were compared to assess clinical performance in a screening setting.

The test's precision (positive predictive value) was 97.41% (95% confidence interval [CI] 92.42–99.15%), and its recall (sensitivity) was 98.26% (95% CI 93.88–99.25%). Specificity was 99.22% (95% CI 97.74–99.74%), negative predictive value was 99.48% (95% CI 97.98–99.87%), and overall accuracy was 99.00% (95% CI 97.69–99.68%).

Agreement between the tests was described by a Kappa coefficient of 0.971 (95% CI 0.947–0.996).

Considering its short turnaround time, low cost, and opportunities for decentralized testing, the researchers concluded that the Ag-RDT could support efforts to control SARS-CoV-2 spread in several settings.