Rapid COVID-19 tests can produce false-negative results, and that's why PCR tests are used as well

Posted at 6:19 AM, Sep 28, 2021
and last updated 2021-09-28 07:19:42-04

GREEN BAY, Wis. (NBC 26) -- This month's rise in COVID-19 cases has put an emphasis on testing. But some are discovering that rapid antigen tests aren't always reliable. On Monday local healthcare leaders discussed how rapid antigen tests can sometimes give inconsistent results.

Most healthcare leaders would agree that molecular testing, PCR tests, are the most accurate COVID-19 tests on the market. But at a time when many people need results now, reliable PCR results often aren't available for days.

"The majority of testing being done in our sites is the PCR test because that's what the state is supplying us," says Dr. Ashok Rai the CEO of Prevea Health.

Doctor Rai says rapid antigen tests can yield results instantly but in some circumstances, the fast rapid tests aren't always accurate.

"You can miss it. Say it's early in the course of the disease or it's somebody without symptoms, it's not as good as PCR is for that reason," says Dr. Rai.

That's why doctors will often give folks both forms of the test. They often give a person a rapid test, and if it yields a negative result, they also have them take a PCR test for good measure.

"Someone who is symptomatic that has a negative rapid antigen test I would want to check and make sure you're getting the antigen test confirmed with a more sensitive molecular test," says Tyler Radke the Lab Manager at Belling Hospital.

Radke says about 16 out of every 1,000 rapid antigen tests taken produce false-negative results. This may give some the impression they don't have the virus, when in fact they do.

"So, when you think about that in sheer numbers; 16 out of 1000 doesn't sound like a lot but it does add up," adds Radke.

That's why even those who get negative test results through the rapid test are often given the PCR test and asked to help contain the spread of the potential virus within them by avoiding others.

"We can do both of these tests and confirm and give them confidence in the results that they actually truly are negative," adds Radke.

Coronavirus in Wisconsin

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More information: COVID-19 on the Wisconsin DHS website

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