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Your Healthy Family: How to avoid a false negative COVID test result

Posted at 7:48 AM, Aug 24, 2022
and last updated 2022-08-24 07:48:23-04

If you start feeling sick and your at-home COVID-19 test comes back negative, it could be a false result. But doctors say at-home tests are still key in fighting the virus, especially heading into flu season.

The Food and Drug Administration says if you take an at-home COVID-19 antigen test too soon after exposure to the virus, your negative result could be misleading. It says it could take several at-home tests before you get definitive results.

"It doesn't mean we shouldn't use them, because when you think about it, if you've got it in your pantry, it's going to be positive most of the time, when you're actually infected," Dr. Robert Schooley, an Infection Disease Specialist with UC San Diego Health, said.

Dr. Schooley said if your initial COVID-19 test is negative, be cautious -- especially if you have symptoms. The FDA says to test again after 48 hours. If the second test is negative, the FDA recommends a third test at home, or a PCR test.

"The key is, if you're worried about being infected, to go ahead and test yourself again," Dr. Schooley said.

He said both tests are reliable, but the at-home test isn't as accurate if people test too early, when the viral load is not high enough to be detected. A PCR test would still pick up the virus once it's sent to a lab for analysis.

"The virus is present in enough quantity to be picked up by the PCR test but it is still below the limit of detection for that antigen test, which is not quite as sensitive," he said.

Dr. Schooley said the at-home tests are still necessary to stop the spread of the virus, and said they'll be especially key during flu season.

"This is going to be important in the winter because influenza is going to be here, and people will have symptoms that are going to be hard to distinguish up front," he said.