How accurate are COVID-19 tests?

COVID-19 nasal swab test. Photo courtesy

The widespread COVID-19 testing is essential to safely reopening the United State, according to most health officials. A big concern has been testing availability, but test accuracy may prove a larger long-term problem.

States have been taking the necessary precautions to combat this virus. Tallahassee has opened several testing sites, including one at Florida A&M’s Bragg stadium.

While this debate focuses on the accuracy of antibody tests, which identify prior infection, diagnostic testing, which identifies current infection, has received less attention.

But false diagnostic tests undermine the efforts at containment of the pandemic.

Diagnostic tests can be inaccurate in two ways. A false-positive result erroneously labels a person infected, with consequences including unnecessary quarantine and contact tracing. False-negative results are more consequential because infected persons who might be asymptomatic may not be isolated and can infect others.

Daija White, a TCC student, went to get tested because she felt under the weather.

”I felt horrible, it was so weird,” she said.

She received a negative result and she believed everything was fine. Given the need to know how well diagnostic tests rule out infection, it’s important to review the assessment of test accuracy by the Food and Drug Administration and clinical researchers, as well as interpretation of test results in a pandemic.

The FDA has granted Emergency Use Authorizations to commercial test manufacturers and issued guidance on test validation. The agency requires an analytic and clinical test performance. Analytic sensitivity indicates the likelihood that the test will be positive for material containing any virus strains and the minimum concentration the test can detect. Analytic specificity indicates the likelihood that the test will be negative for material containing pathogens other than the target virus.

“This inaccuracy with testing is definitely scary and I hope soon it is all fixed,” said Emmanuel Childs, a student at Florida A&M University.

Clinical evaluations, assessing the performance of a test on a patient’s specimens vary among manufacturers. The FDA prefers the to use the term “natural clinical specimens,” but has permitted the use of “contrived specimens” produced by adding viral RNA or inactivated virus to leftover clinical material. Ordinarily, test-performance studies entail having patients undergo an index test and a “reference standard” test determining their true state.

“If the test isn’t accurate how do we know who really has COVID-19,” Florida State student Jaden Vilvert said.

The continuation of known false negatives may lead to overestimates of test sensitivity, along with putting the community at risk.

We have a long way until we will see the end of COVID-19. That, almost everyone, can agree on.