How accurate are at-home COVID-19 tests?

Published: Jan. 17, 2022 at 5:53 PM CST
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EAU CLAIRE, Wis. (WEAU) - With record COVID-19 case numbers in Wisconsin according to the state Department of Health Services, many people are looking for at-home, rapid antigen tests to determine if they have the virus.

However, these tests may not always detect the Omicron variant according to the Centers for Disease Control and Prevention.

“Rapid test effectiveness depends on why you’re doing them,” Prevea Health Chief Medical Officer Dr. Ken Johnson said.

He said it’s accurate when used by people who are symptomatic and test positive. People who are feeling sick and test negative could still have and spread COVID-19.

“A rapid test looks only for the virus,” Johnson said. “And so if you’re early in disease and not shedding a lot of virus yet, it will be negative. That’s why the kits come with two tests, one to test now and one to test in a day or two to make sure you’re not missing that or getting a false negative with the first test.”

He said the test is fairly accurate for people take it after five days if they don’t have symptoms.

Though antigen tests are more convenient, delivering results within minutes from home, Johnson said a PCR test is more accurate when someone first gets the virus.

“The difference between a PCR test and an antigen test is an antigen tests only looks for the amount of virus that’s there right now,” he said. “PCR actually replicates the DNA-RNA material, so it takes a small amount and makes it into a larger amount so it’s more easy to find it.”

He added the downside with PCR tests is they take longer to get results. There are also fewer available as Omicron spreads.

“We are stretched to a point where we cannot do PCR tests on everybody that wants one so an antigen test is a good back-fill into that,” Johnson said.

He said regardless of what someone’s results say, they should isolate if they’re feeling sick.

“Isolate for five days anyway because even if it’s not COVID, it’s some infectious illness you can still spread,” he said.

Johnson said doctors are seeing many flu and RSV cases.

The State of Wisconsin is requiring all insurance companies cover the cost of at-home over-the-counter rapid tests.

President Joe Biden announced at-home tests will soon be available by mail to people for free.

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