Virus tests are categorized based on what they look for: (i) molecular tests, which look for the virus’s genetic material; and (ii) antigen tests that look for viral proteins. The various tests all use a sample collected from either the nose, throat, or mouth; that may be sent away to an outside lab or processed on-site within minutes. Here are the common tests and some of the pros and cons of each.
Laboratory molecular test. The most widely available test is the P.C.R. (polymerase chain reaction) test. It looks for bits of the virus’s genetic material. This test is considered the gold standard of coronavirus testing because of its ability to detect even very small amounts of viral material. A positive result from a P.C.R. test almost certainly means you’re infected with the virus. Because these tests have to go through an outside laboratory, the typical turnaround time is a few days, which can limit this test’s usefulness, since you may be spreading virus during the waiting period. Another frustration of P.C.R. testing is that it sometimes detects the virus’s leftover genetic material weeks after a person has recovered and is no longer contagious.
Rapid molecular test. Some tests combine the reliability of molecular testing with the speedy results of a rapid test. Abbott’s ID Now relies on a portable device that can process a molecular test right in front of you in less than 15 minutes. These tests are speedy and highly sensitive, and they can identify those exposed to coronavirus about a day sooner in the course of an infection than a rapid antigen test (described below). A rapid molecular test isn’t quite as accurate as of the laboratory version, but you’ll get the result much faster. Like its laboratory cousin, a rapid molecular test can detect leftover genetic material from the virus even after you’ve recovered.
Rapid antigen test. An antigen test identifies pieces of coronavirus proteins; not the virus itself. Antigen tests deliver results in 15 to 30 minutes. An antigen test is less likely than P.C.R. to find the virus early in the course of the infection. A negative antigen test won’t tell you for sure that you don’t have the coronavirus — it only tells you that no antigens were detected, so you’re probably not highly infectious today. In one study, a rapid antigen test missed 20 per cent of coronavirus infections found by the lab-based P.C.R. test. Antigen tests also have a higher rate of false-positive results, so a positive rapid test should be confirmed with a P.C.R. test.
AFC Urgent Care offers both the outside lab P.C.R. test and the rapid molecular test via the Abbott ID Now device. As such, AFC’s rapid testing offering is significantly more accurate than others offering the far less reliable rapid antigen test.
