The Diagnostic or PCR test is used by doctors to diagnose people who are currently sick with the COVID-19 virus.
How does the PCR test work?
Typically, this test can be conducted at a drive-through testing site from the comfort of your own car. The test is conducted by taking a sample of mucus from the patient by inserting a cotton swab into their nose canal. The PCR test looks for active genetic material of the COVID-19 virus, which if found, means that the person is infected.
Even though the PCR test can deliver results in less than 24 hours, most testing hubs will send out the samples to specialized labs to run the tests, this means that results typically take between 4-7 business days to be delivered.
How accurate is it?
Currently, the Diagnostic or PCR tests are the most accurate ones out there, which makes them very reliable. This test however does not tell you if you’ve had the COVID-19 virus in the past, it will only deliver results if there is an active infection going on.
There are times in which it may take the virus a few days to start replicating or spreading throughout the nose and throat, this means that if someone is recently infected, the nose swab may fail to pick up signs of an active infection.
Sensitivity – 95% https://www.fda.gov/media/136151/download
The Antigen test is primarily used to detect proteins (antigens) from SARS2-CoV-2 nasal swab specimens from individuals who are suspected of COVID-19.
How does the Antigen Test work?
This test is conducted in a similar way to the PCR test which is by collecting a patient’s sample from the throat or nose canal by using a swab, where the virus likes to hang out, this test is similar to a strep rapid test that is done at any doctor’s office. This test looks for proteins that come from the COVID-19 virus that are called antigens. This type of test can be considered as a more straight forward diagnostic test.
The new recently FDA approved test by Quidel Corp. usually takes around 15 minutes to process and deliver the results. The rapidness of the test allows medical professionals to screen may people in family clinics or hospitals to determine if someone is currently at high risk of spreading the COVID-19 virus.
How accurate is it?
Quidel Corp. got an emergency granted FDA approval on May 8th, 2020 for their antigen test. Many researchers and medical professionals have expressed that they do not expect the antigen test to be as accurate as the PCR diagnostic test. The test itself is 93.8% sensitive.
Depending of the clinical history, some patient might need to get a confirmation PCR test to make a proper medical diagnosis.
A positive test result indicates that antigens from SARS-CoV-2 were detected and patient is infected with the virus and presumed to be contagious. The specificity of this test is 100%, which means a 0% rate of false-positive results.