PCR vs. Antigen COVID Testing: What You Need to Know

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Finding a COVID-19 test has become a real challenge with the spread of the omicron variant.

But there is also confusion over which test people should be getting, which is a PCR or antigen?

“The two big tests we have available right now are the Antigen test. That’s the at home test, its usually very rapid and the PCR test. That’s the test that we use in the hospital,” said Dr. Peter Chin-Hong, an infectious disease specialist at UCSF.

Chin-Hong added that there are different reasons people get the different tests as they certainly get the test that is easily available to them. He also said the PCR tests are more sensitive than the antigen or rapid test.

“One way of thinking about when you might do a rapid test for sure if you have symptoms later on in the course of the disease,” Chin-Hong said. “Definitely three days or so, after exposure early on you’re not going not going to pick it up positive on the at home antigen test and the PCR test may be positive.”

Chin-Hong said both tests are good for picking up the virus when you have symptoms. But the PCR is going to detect the virus sooner, but people will have to wait for results.

“The easy part about a rapid test is that it’s easier to do you’re doing it in the comfort of your home its instant like 15-30 minutes,” he added, “Right now, with the lines in PCR test you may get that result back in two days, sometimes three days, in which case you have to be careful to not go around and transmit virus and assume you are positive if you have symptoms. With at-home tests, a user’s method matters too and making a mistake can mean getting a false negative.”

While the PCR test has a longer turnaround time, but it has an higher accuracy rate.

“The PCR test is really good to confirm a diagnosis…like say you have the sniffles and you did an antigen test and it was negative but you’re kind of suspecting it because everyone you were with at that dinner party all turned positive,” said

Experts said if you're trying to figure out if you've cleared the virus, look for an antigen test. That's because PCR testing can still detect traces of the virus for weeks or more.

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