Taking an at-home COVID test at the right time lowers chance of false negative, experts say

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Posted at 6:17 AM, Dec 31, 2021
and last updated 2021-12-31 06:19:42-05

CLEVELAND — These days, snagging an at-home COVID-19 test feels like a feat, but it could be all for naught if you test too soon after a known COVID-19 exposure.

Mondi Alailima knows that well. The Fairview Park woman’s son was exposed to COVID-19 the Monday before Christmas.

“He started showing symptoms Thursday, decided to test of Friday, and he tested positive,” she said.

He lives at home, so she figured she would test too.

I wasn't planning on going anywhere, that wasn't why I decided to test. It was more out of curiosity just to make sure, you know, if I had it or I didn't have it and decided to be prepared for what may come,” said Alailima.

She tested negative on Christmas Eve, but by Monday she was bedridden with all the typical COVID-19 symptoms: fever, body aches, chest pain, cough and more.

“Thirty-six hours later, I started showing symptoms, and I’m like, 'Well, okay. I guess I’m not negative,'” she said. “If you test prematurely, then you can still be infected, but you are not in that infectious phase, you are not showing symptoms yet. That's what happened with me. It was negative, but I was on my way into a positive result.”

Donna Skoda, the health commissioner for Summit County Public Health, said timing is everything when it comes to at-home antigen test kits.

“It [at-home testing] is not as sensitive as the molecular PCR test, that's considered like the gold standard because it is extremely sensitive to SARS-CoV-2," she said. "The antigen test, however, is not as sensitive, so it has a little more wiggle room and it has a little more where you could get a wrong result.”

The time to at-home test after a known exposure varies, but in the meantime, avoid other people and wear a mask.

If you’re fully vaccinated, wait about 5 days after an exposure to test.

“Because I'm vaccinated, I may not get as quick of a viral load and it might not be picked up,” Skoda said.

For the unvaccinated, or those eligible for a booster who haven’t received one yet, test within 2 to 3 days after you’ve been exposed.

Romona Brazile with the Cuyahoga County Board of Health said the problem with at-home tests is that people are testing too soon.

“A lot of times people kind of freak out and they test immediately, which may give them a little bit of false reassurance that, you know, they're not positive,” she said.

If you’ve already received a negative result but then symptoms develop, you should take another, no matter the vaccination status.

“The viral load is going to be the highest right before you start to feel sick and when you first start to really feel it, those first couple of days,” said Brazile.

But Skoda said there’s little room for error if you get a positive.

Alailima and her son are on the mend and feeling better, but she wanted to warn others in the community to be safe and informed when taking an at-home test.

“I would just hate for someone to spend so much time out there trying to find a test. They finally get them, test to where they think it's negative, and then it starts a domino effect from there,” she said.

Skoda said other tips for getting an accurate result: take a good sample.

“You really have to make sure that you swirl [the swab] around so that you get a good test,” she said.

She also said to make sure your tests have the emergency use authorization label from the FDA.

And if you want to make sure your negative result is accurate, try to find a molecular PCR test at a clinic or pharmacy.

“They're sent away in a viral lab and they're analyzed,” said Skoda.