Polymerase chain reaction(PCR) is a sensitive Laboratory technique that can detect Coronavirus in a sample of mucus typically taken from a person’s nose or throat.
Doctors use this test to diagnose people who are currently sick with COVID-19. This is the one we’ve been hearing so much about.
The test may also work on saliva that’s under investigation. It looks for the genetic material of the coronavirus. The test uses a technology called PCR (polymerase chain reaction), which greatly amplifies the viral genetic material if it is present. That material is detectable when a person is actively infected.
Generally speaking, these are the most reliable tests. However, a few days may pass before the virus starts replicating in the throat and nose, so the test won’t identify someone who has recently been infected. And swabs can sometimes fail to pick up signs of active infection.
How quick is it: These samples are generally sent to centralized labs for analysis, so it can take several days to get results back. Wait times were longer earlier in the pandemic because of a testing backlog.