Antigen vs. PCR: what to make of different types of COVID-19 tests

With a new surge of COVID-19 cases underway and elected officials urging people to get tested, many coronavirus testing sites in the D.C. region are filling up fast with long lines.

We've heard a lot about different types of coronavirus tests –– PCR versus the antigen-rapid tests –– but are they both just as accurate?

READ MORE: Need for COVID-19 testing grows in DC region as cases surge nationwide

"The diagnostic tests, there are a few. The PCR test, those molecular tests are generally more sensitive and they are better tests to have, because they tend to be more accurate. Those tests are looking for the virus's genetic material," said Dr. Amira Roess,  an infectious disease expert and professor at George Mason University.   
She adds, "Then you have the antigen tests-- the ones that are looking for the virus's protein, those tests tend to be less reliable.. Many can turn around results very quickly, which are not as accurate and should be interpreted with caution."  

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The “gold standard” for clinical diagnostic detection of sars-cov-2 is the PCR test--  where samples of mucus are taken from a person's nose or throat. These samples are generally sent to labs for analysis,  so it can take several days to get results back.

Antigen tests are relatively inexpensive, they are taken with a nasal or throat swab, and they don't require a traditional lab so results can return in approximately 15 minutes. They're best for screenings in high-risk congregate settings but Dr. Roess says it's best to follow it with a confirmation test.