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Doctors warn about false negatives when taking at-home COVID-19 tests

COVID-19 tests
Posted at 6:56 AM, Dec 30, 2021
and last updated 2021-12-30 15:00:43-05

At-home COVID-19 testing kits have been hard to find. But even for those who can find them, the FDA says they may not always be able to detect the omicron variant.

That opens the door for false negatives.

So, as Americans get ready to celebrate New Year's, doctors are urging people not to immediately assume they're in the clear after a negative at-home COVID-19 test.

"The problem with the at-home tests is that the false negativity rate is about 20%," said Dr. Asha Shajahan, the medical director of community health at Beaumont Grosse Pointe in Michigan.

Shajahan said roughly two out of every ten negative at-home test results are actually positive. That number may be even higher when it comes to the omicron variant.

"Just going by one home test, since the false-negative rate is so high, it could falsely mislead you to believing you're negative when actually you are positive," Shajahan said.

During a White House COVID-19 response team briefing on Wednesday, Dr. Anthony Fauci said that he still recommends the use of at-home tests, even if the omicron variant poses issues.

"In some of the tests, there appears to be somewhat of a diminution, not a disappearance, but a diminution of the sensitivity," Fauci said.

Shajahan says at-home tests are more accurate when used over multiple days when a person is symptomatic. That's because at-home tests measure for antigens.

"The antigen test is actually testing your immune response to the virus and it's a one-time immune response that it's testing," Shajahan said. "Whereas the molecular test, which is what the PCR test is, does viral replication, so it tests it multiple times, so it's more accurate of a test."

Experts also agree that it's extremely rare for an at-home test to deliver a false positive test.

Doctors say the best way to limit the spread of COVID-19 this New Year's is to get a PCR test. Fauci on Wednesday also said Americans should avoid large parties and instead host smaller at-home parties with other vaccinated friends and family.

This story was originally published by Jenn Schanz on Scripps station WXYZ in Detroit.