What is the difference between an antigen test and a PCR test?

An antigen test is frequently referred to as a rapid test. This test detects protein fragments specific to the Coronavirus. Turnaround time for results is usually very quick and in some cases, results can be reported within 15 minutes.

In the rapid test, a sterile swab is carefully inserted into the patient’s nostril exhibiting the most visible drainage or the nostril that is most congested if drainage is not present. The swab is gently rotated five times or more against the nasal wall and slowly removed from the nasal cavity. Using the same swab, sample collection is repeated in the other nostril. The point-of-care testing card is opened and placed flat on a counter. While holding the extraction reagent bottle vertically ½ inch above the test card, the tester will place six drops of reagent solution in the top hole of the swab well. The tester will insert the sample swab into the bottom hole of the test card and firmly push upwards so that the swab tip is visible in the top hole. The swab will be rotated clockwise three times to disperse the reagent.  The test card will be sealed shut via adhesive strip, and read through the test window after 15 minutes, but no later than 30 minutes as this may lead to false results. The test is positive if two pink/purple lines appear in the result window (even a faint line is considered positive). A negative test will give a single pink/purple line. The test results can help healthcare professionals to make appropriate decisions quickly.

The PCR test is considered the “gold standard” in SARS-CoV-2 detection. This test actually detects RNA (or genetic material) that is specific to the virus and can detect the virus within days of infection, even those who have no symptoms. Turnaround time is typically a few days but may take up to a week especially when demand is high. 

The PCR testing process is very similar to the method for rapid antigen test collection.