Most commercially available COVID-19 molecular assays detect the SARS-CoV 2 virus using nucleic acid amplification tests (NAATs), which detect one or more viral ribonucleic acid (RNA) genes. NAATs detect a particular nucleic acid sequence in the virus’s RNA rather than antigens or antibodies. The viral nucleic sequence is amplified to create millions of copies of the specific sequence. For most molecular tests available for COVID-19, the amplification of RNA specific to the SARS-CoV-2 virus is accomplished using the polymerase chain reaction (PCR). Most of the commercially approved PCR-based COVID-19 tests use the technique of real-time reverse transcription polymerase chain reaction (real-time RT-PCR).
NAATs, such as real-time reverse transcription-polymerase chain reaction (real-time RT-PCR), are high-sensitivity, high-specificity tests for diagnosing SARS-CoV-2 infection. NAATs detect one or more viral ribonucleic acid (RNA) sequences and indicate a current or recent infection. However, due to prolonged viral RNA detection, they are not always direct evidence for the presence of a virus capable of replicating or being transmitted to others. Most NAATs need to be processed in a laboratory and the time to results can vary (1–3 days), but some NAATs are point-of-care tests with results available in about 15–45 minutes. Most NAATs produce qualitative results.
