Coronavirus Tests Offer Competing Benefits: Speed vs. Accuracy

Molecular tests and antigen tests can both be trusted with positive results, per the FDA. But the rate of false negatives with rapid tests can be a concern

NBCUniversal, Inc.

More than 50 million Americans have been tested for the coronavirus as of Wednesday, according to data reported by the Centers for Disease Control and Prevention.

The majority of those tests, known as diagnostic tests according to the Food and Drug Administration, are designed to accurately answer the question of whether that person is currently infected with COVID-19.

But the accuracy of those tests can range significantly, depending upon which type of test one takes, according to the CDC.

Molecular tests are the most accurate, according to the FDA, and involve a throat or nose swab, or, as with a newly-opened testing site in Fort Worth, a saliva sample. Those samples are then sent to a lab for tests, and results are typically given with days or upwards of two weeks.

Antigen – or rapid – tests can often produce results within as little as 20 minutes, according to the FDA, and a positive result is considered to be highly accurate.

But the primary concern with rapid testing is the prevalence of false negative results, where an infected person is told they do not have COVID-19.

Those false negatives concern some in public health, including Dr. Philip Huang, Director of Dallas County Health and Human Services.

"I have a low level of confidence in the rapid tests,” Dr. Huang said.

Other medical professionals have stopped short of recommending one particular type of test over another but stressed that accuracy is of the utmost importance.

“My dream test would be one that is non-invasive, accurate, fast, and convenient,” said Dr. Susan Bailey, a Fort Worth allergist who is President of the American Medical Association. “But the accuracy of any test is the most important factor.”

In light of the increased likelihood of false negative results on the rapid tests, guidance from the FDA advises someone who is showing symptoms of the coronavirus, but gets a negative result, to seek out a second, molecular test.

Contact Us