FDA recommends repeated at-home testing until positive result reached

The Food and Drug Administration updated its guidance this month to recommend that anyone who receives a negative result from an at-home COVID-19 antigen test continue testing until it shows positive. The recommendation applies whether the individual is experiencing symptoms or not. 

"The U.S. Food and Drug Administration (FDA) is advising people to perform repeat, or serial, testing following a negative result on any at-home COVID-19 antigen test, to reduce the risk an infection may be missed (false negative result) and to help prevent people from unknowingly spreading the SARS-CoV-2 virus to others,” says the FDA on its website. “The FDA recommends repeat testing following a negative result whether or not you have COVID-19 symptoms.” (emphasis original) 

The agency does not specify that this recommendation is only for those who may have been exposed to the virus, suggesting that everyone should test repeatedly until one shows positive. 

According to the FDA, negative results can be false, but positive results are almost always reliable. 

“When you perform an at-home COVID-19 antigen test, and you get a positive result, the results are typically accurate. However, if you perform an at-home COVID-19 antigen test, you could get a false negative result.” 

The Quidel Sofia Sars antigen test insert says the test was authorized for "individuals who are suspected of COVID-19 by their health care provider within the first five days of the onset of symptoms," not for an asymptomatic person.

However, the agency then appears to suggest that those with symptoms test at least twice, while those without symptoms should perform at least three tests. 

“If you receive a negative result, the test did not detect the SARS-CoV-2 virus at the time of that test. If you have COVID-19 symptoms, test again 48 hours after the first negative test, for a total of at least two tests. If you get a negative result on the second test and you are concerned that you could have COVID-19, you may choose to test again 48 hours after the second test, consider getting a laboratory molecular-based test, or call your health care provider.” 

But someone who has no symptoms should “test again 48 hours after the first negative test, then 48 hours after the second negative test, for a total of at least three tests. If you get a negative result on the third test and you are concerned that you could have COVID-19, you may choose to test again using an antigen test, consider getting a laboratory molecular-based test, or call your health care provider.”