Bryan Health expert discusses accuracy of COVID-19 testing, false negatives
A Bryan Health expert says it's possible up to a third of all COVID-19 test results could be false negatives.
A Bryan Health expert says it’s possible up to a third of all COVID-19 test results could be false negatives.
Dr. Jim Nora, medical director of infection prevention at Bryan Medical Center, said that number could be less – but it’s probably not zero.
Nora said the difficulty with direct molecular tests – the kind being used in Nebraska and across the globe – a specimen of the virus must be present in order for the test to provide an accurate result.
For example, with COVID-19 testing, a swab is stuck in a patients nose and twisted to get cellular debris which is sent off to be tested.
The problem, Nora says, is there is a short window of opportunity to test. If a test is performed too early or too late, there may not be any virus present – which is necessary for an accurate result. Nora said it’s unknown what that time frame is.
The testing issue could explain why some people received a negative COVID-19 test result despite displaying some or all of the symptoms.
Some good news – Nora says he doesn’t believe there is an issue with false positive tests. He said doctors have a lot of confidence in positive results, and that he has heard of no reports where a false positive result was given.
So, if someone tests negative but still has coronavirus symptoms, what should they do? Nora says the best thing is to self-isolate at home. If a person’s symptoms don’t improve, Nora says they should consult with a primary care provider to determine if there’s an alternative explanation (like influenza) for the symptoms.
Nora says serology tests can be used and are more likely to provide accurate results. Such tests are not currently widely available, he said.