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Melissa Miller, PhD, director of the Clinical Molecular Microbiology Laboratory at UNC Medical Center, talks with the News and Observer about why an at-home COVID test might give false-negative results and tips on how to determine if follow-up testing is needed.


Melissa Miller, PhD, director of the Clinical Molecular Microbiology Laboratory at UNC Medical Center, talks with the News and Observer about why an at-home COVID test might give false-negative results and tips on how to determine if follow-up testing is needed.

“Whether a COVID test returns positive or negative results depends largely on two factors: the sensitivity level of the test and the viral burden of the disease in your body when you take a test,” Dr. Miller said.

If you’re experiencing COVID symptoms or have been exposed to the virus, at-home rapid tests are a relatively easy and convenient way to determine whether you have the virus — but it’s worth noting that they are less sensitive and have a higher risk for false negative results than lab-based PCR tests, such as those you might be tested with at a COVID testing site or in a health care setting. That means, in relation to how long you’ve been experiencing symptoms or how long it’s been since you were exposed to the virus, PCR tests will return positive results for COVID before an at-home test does.

“A PCR test, being more sensitive, is more likely to detect the virus earlier, when your body’s viral burden is at a lower level, compared to an at-home test, which likely will not detect the virus until later, when the viral burden reaches its peak,” Dr. Miller said.

Dr. Miller adds that at-home tests are an excellent way to confirm a symptomatic infection is COVID, if positive.

You can read more here about what to do if you have COVID symptoms, but test negative, tips on what to do while you’re experiencing those symptoms, and best practices when using at-home COVID tests.