There is confusion using the term “rapid test.” The proper distinction to make is between a point-of-care versus an in-lab test. Current testing methods to detect COVID-19 include culturing, PCR, and antibody/antigen testing.
Culturing is not an option for this virus for many reasons and has been prohibited for COVID-19 use.
Antibody and antigen testing are generally rapid and available as a CLIA waived point of care test. Antibody and antigen testing can be put together via lateral flow paper chromatography cassettes which can be used as a point-of-care test with results in 10-20 minutes. Many people consider this as the “rapid test”. These tests tend to have poor sensitivity—typically 60-70%. These tests require an antibody response which takes days and makes this test not useful for detecting an infection.
PCR is the gold standard and is generally considered a highly complex test performed in a lab. PCR identifies the pathogen genetically and is very sensitive and specific. This is the only test that can accurately and timely identify the pathogen. Our PCR lab can test over 400 samples per hour and detect as few as 1-5 copies of RNA per sample.
There are a few point-of-care tests that utilize PCR technology. These point-of-care PCR tests can run 1 test at a time to detect a single pathogen, and it takes 15 to 90 minutes to run depending on the machine. These tests require the purchase of a machine and proprietary consumables to operate which make it somewhat expensive. These devices tend to have a higher level of detection, usually 100-200 copies of RNA per sample. While these are convenient and quite good, if the sample contains a lower amount of pathogen, there is a greater chance it will get missed. We use commercial machines from very well established companies, Bio-Rad and Thermofisher. In addition, we employ automation in order to limit human error which can be significant when handling very low volumes and when introducing contamination.