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UVA doctor explains why a negative COVID-19 home test may not be reliable

Published: Jun. 15, 2022 at 11:36 AM EDT
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CHARLOTTESVILLE, Va. (WVIR) - Your negative at-home COVID-19 test might not mean anything now. More doctors are questioning the accuracy of these tests.

“People anecdotally are reporting testing negative two to three days even after their symptoms started,” Doctor Amy Mathers with UVA Health said. “I think something is changing a bit”

Dr. Mathers has been studying COVID-19 and its various tests since the beginning of the pandemic. Even this stumps her.

“There’s even scientific papers showing that sometimes people are testing positive by antigen five days after symptoms start. And so it really depends also on the antigen test that you’re using,” Mathers said.

The problem is they don’t know which antigen test works best now as variants constantly change.

“There’s some data showing that omicron may test positive, this has not been borne out by every study, but that you may test more positive by a throat swab than you would buy a nasal pharyngeal,” Mathers said.

Though she says she does not recommend using a nasal test as a throat one if that is not what the directions say.

She says we have to take a step back and reevaluate the way we are doing this.

“You cannot rely on an antigen to think, especially when you have symptoms, to think that you don’t have COVID and you really need to go get a PCR test,” Mathers said.

She says the at-home tests have a different chemistry to target the virus differently, and with recent variants the detecting has been weaker.

“If you’ve taken a test two to three days later, and it’s still testing negative by antigen, I would really still mitigate your activities,” Mathers said.

Dr. Mathers says it is always best to get a PCR test if you have symptoms.

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