Why at-home tests are coming up negative despite COVID-19 infection

For some people with COVID-19 infections, at-home tests are providing faulty results, showing a negative result when the person is truly positive.
For some people with COVID-19 infections, at-home tests are providing faulty results, showing a negative result when the person is truly positive. Photo credit Getty Images
By , KCBS Radio

For some people with COVID-19 infections, at-home tests are providing faulty results, showing a negative result when the person is truly positive.

Dr. Dean Blumberg, UC Davis Health infectious disease specialist, told KCBS Radio's "Ask An Expert" there may be lower concentrations of the antigen at the beginning of the infection, causing people to test negative.

"That can be very frustrating because you think you’re doing the right thing by testing, and then when you test negative sometimes you just go about your usual activities only to find out later you were infectious," said Blumberg. "This has been happening, I've been hearing about this from other people also, and it’s possible that the tests just aren’t picking it up early on."

He gave a quick reminder that the antigen test, which is the at-home test, is about 80% sensitive, so they are going to miss some cases.

As well as the at-home test’s accuracy, Blumberg said vaccinations may also have something to do with the negative results.

"It's possible that the vaccinations lead to immunity that results in a lower concentration of the antigen, and therefore the test might not be as sensitive," he explained. "The omicron variant does behave differently than the previous variants in that it does cause less invasive disease, it appears to cause less severe disease, and that might interfere with the detection by our commonly used tests."

LISTEN on the Audacy App
Sign up and follow Audacy
Facebook | Twitter | Instagram