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'Faster doesn't mean better' | Rapid COVID-19 testing not as reliable as traditional tests, experts say

The FDA encourages those who take rapid antigen tests to get a second test to confirm the results.

HOUSTON — As COVID-19 cases continue to climb in Texas, so are the number of people getting tests and there are lots of options. But not all COVID-19 tests are created equal. Some are more accurate than others. 

Across Houston more urgent care centers and community clinics are offering rapid COVID-19 testing, promising results as fast as 15 minutes. 

"You can equate to if you go to a fast food place or a gourmet restaurant," said Joe Petrosino, Chair of Molecular Virology and Microbiology at Baylor College of Medicine. 

Petrosino says faster doesn't mean better. 

"You have to be careful if you're going to use rapid testing for your determination to see if you have the virus," said Petrosino. "Those tests that run on short turnaround times, some run 5 minute to 45 minutes to an hour, they have less sensitivity and give a lot of false negatives."

That means you could have the virus and the test didn't catch it. Petrosino says most people think all COVID tests are the same, but they're not. Rapid tests may be giving patients a false sense of security. 

"I don't think there's a lot of awareness about the differences between rapid tests and the more traditional lab, send it out, 24 to 48 hour results type tests," said Petrosino. "It's very important to know the difference. If you go to a rapid clinic and come out with a negative result, you think you're okay and you could be exposing and putting a lot of individuals at risk."


The most reliable tests are those sent to labs for processing in 24-48 hours like the ones administered at free city and county sites. Most of these PCR lab tests are in the upper 90th percentile for accuracy. 

"Some of the tests in rapid test clinics can be lower than 80 percent in terms of predictive value," said Petrosino. 

Even the FDA warns rapid antigen test results "may need to be confirmed with a PCR test prior to treatment decisions..." Petrosino's advice is always to consult your doctor first, but a backup test after a rapid test could be a good idea.

"Unless there's a hurry or a rush need, a testing center that sends your test to a lab where its due back in 24-48 hours, those are the ones you can rely on a bit better than rapid tests," said Petrosino.