If you tested negative for COVID then tested positive days later, you are not alone

Health officials say you should not rely on a single negative test result to believe you are free of the virus
Published: Jan. 17, 2022 at 4:42 PM CST|Updated: Jan. 17, 2022 at 6:08 PM CST
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NEW ORLEANS (WVUE) - If you are experiencing any symptoms of COVID-19, doctors say you should just assume you have it and stay home.

“It doesn’t have to be COVID, but if you’re symptomatic, I wouldn’t rely on a single negative test to believe that you’re negative, especially if this is one of the home tests,” said Dr. Lucio Miele, chair of the Department of Genetics at LSU Health.

Miele said when it comes to testing for COVID-19, there’s a tradeoff: home tests or rapid antigen tests are fast, but not always accurate. PCR tests can take days for results to come in but are more likely to detect the presence of the virus.

“You can only have one of the two: speed or accuracy. You can’t have both,” said Dr. Miele. “And there isn’t a test in the world that will have both.”

He said the best way to detect the virus is to test repeatedly, especially if the patient is symptomatic--which is why many home tests come with at least two kits.


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But the question remains: Why can’t the virus be detected on first try with home tests and rapid tests?

“If you do the test at a time when the viral load is low in the nose, then you’re less likely to pick it up,” said Dr. David Mushatt, chief of adult infectious diseases at Tulane School of Medicine.

Mushatt said when it comes to the COVID-19 virus, timing is everything. The amount of virus present in the body changes over time; increasing as symptoms begin to appear.

“No test is 100 percent in medicine. Very few tests,” he said. “All tests have a limit to sensitivity and specificity, which means they can’t have false positives. But when you have a lot of the virus going around, as we do right now, false positives are quite rare.”

So if you test negative at first, and you’re still experiencing symptoms, like cough, sore throat, and nasal drip, health officials say you should assume you are infected with COVID-19.

“Do not go to work sick assuming that you don’t have it,” said Dr. Miele. “And also don’t make this assumption ‘Oh I had it five months ago, so it’s gotta be something else.’ That’s not true, not with this variant.”

Dr. Mushatt said if someone tests negative for COVID and tested multiple times, there are other respiratory illnesses going around like the flu which can be tested.

In most cases, Mushatt says the patient will likely receive a prescription for an antiviral flu medication which can help shorten the duration of illness.

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