The differences you need to know about PCR and rapid antigen COVID-19 tests

Testing is crucial to help stop the spread of COVID-19
At home covid test
Posted at 1:48 PM, Jan 21, 2022
and last updated 2022-01-21 17:29:49-05

(WXYZ) — Now that the government is offering free COVID-19 testing kits to all Americans, many may have questions about how accurate these tests are and when they should be taken. 

Both the PCR and Antigen tests can detect an active case of COVID-19. The main differences between the two involve the timeframe and the accuracy.

The PCR test is considered the most reliable because it can identify minimal amounts of the virus’s genetic material in a person’s specimen. For that reason, the Centers for Disease Control says the PCR test is more precise at diagnosing COVID-19 in a person who has been recently exposed.

However, the flip side is that the PCR is so sensitive that it may show positive results several weeks after the individual has recovered and is no longer contagious.  

Meanwhile, the rapid antigen test is less sensitive. It only picks up viruses at higher levels and can help identify when a person is more infectious.

The general thought is to get a PCR test when you know or suspect that you have been exposed to a person with COVID-19. You should also get this test if you are having symptoms and you want to find out if it is a coronavirus infection.
It does take longer to get the results of a PCR test, but it is more accurate.

The earlier you know your COVID status, the better. You can take the proper precautions, such as isolating and informing the people you’ve had contact with. Remember, you are at the highest risk of infecting others up to two days before symptoms appear and a couple of days after the symptoms begin.

Rapid antigen test should be taken after you’ve had COVID-19 for several days and you want to confirm that you are no longer infectious to other people. For example, if you have been isolating for five days, the CDC recommends you take the rapid antigen test at that point to see if you are still positive.

Regardless of which method you choose, testing is crucial to help stop the spread of COVID-19. So, if you have concerns about a recent exposure or you’re not feeling well, get tested for yourself and your loved ones.

Additional Coronavirus information and resources:

View a global coronavirus tracker with data from Johns Hopkins University.

See complete coverage on our Coronavirus Continuing Coverage page.