Antigen vs. PCR tests for COVID-19: What’s the difference?

What is antigen testing?

BIRMINGHAM, Ala. (WBRC) - If you want to know if a person is infected with the coronavirus there are two major tests right now. Both have pros and cons. The antigen test goes looking for an antigen or a protein of the COVID 19 virus. The PCR test checks for the genetic material of the virus detected in a person.

“The PCR test is a bit more sensitive picking up more of people infected than the antigen test,” Dr. Michael Saag, Director UAB Infectious Diseases Division said.

The PCR tests takes at least 24 hours to get results and the antigen test has a slightly higher degree of providing false negative tests. But there are positives for using the antigen test.

“The benefit with these is because they can be done in the office. They don’t have to be sent off you can get the results very easily and it’s easier to test people again if you have suspicion.” Dr. Wesley Willeford with the Jefferson County Health Department said.

Dr. Willeford said the antigen test was good when it came to testing people with symptoms. “The hard part is where you have people who are not having symptoms or they were recently exposed that is where it’s not quite as good as the PCR test,” Willeford said.

Despite the drawbacks, Dr. Saag said NCAA conferences , like the Big Ten, who recently decided to move forward with college football based on protocols mandating regular antigen testing of players, will be able to make up for the shortfalls of antigen tests by testing frequently.

“If you are testing people daily, the false negative rate is becoming less important because you are doing it over and over again,” Saag said.

The antigen test is quick and cheaper than the PCR test. Dr Saag and Willeford said another test, a card test, that uses salvia can be tested quickly. Saag hopes to see this tests in nursing homes and even schools soon.

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