As COVID-19 tests become more widely available across the US, scientists have warned about a growing concern: Many people with negative results might actually have the virus.
"It depends on how much virus the person is shedding , how the test was collected and whether it was done appropriately by someone used to collecting these swabs, and then how long it sat in transport," she said. But even if it were possible to increase the sensitivity to 90 percent, the magnitude of risk remains substantial as the number of people tested grows, Sampathkumar argued in a paper published in Mayo Clinic Proceedings.
The main nasal swab tests examine the nasopharynx, where the back of the nose meets the top of the throat. This requires a trained hand to perform and some portion of the false negatives arises from improper procedure. This was done on a patient whose nasal swab returned negative three times, but who showed all the signs of COVID-19.