Fact checking claims about COVID-19 PCR tests with Matthew Binnicker, Ph.D.

Feb. 5, 2021

In late January, the digital publication FactCheck.org investigated online claims that the World Health Organization (WHO) recently changed its guidelines for COVID-19 testing and admitted that previous case counts had been inflated — claims the fact checkers found to be inaccurate.

The subject of the bogus claims was a WHO memo dated Jan. 20. The document was intended for laboratory professionals, and it reminded them to carefully follow the manufacturer directions for COVID-19 polymerase chain reaction, or PCR, tests to prevent false-positive and false-negative results. 

Among the experts that FactCheck.org consulted in its exploration of the WHO memo and the inaccurate information that arose from it was Matthew Binnicker, Ph.D., director of the Clinical Virology Laboratory at Mayo Clinic in Rochester, Minnesota.

Dr. Binnicker addressed the erroneous assertion that the memo implied PCR tests were producing false-positives due to high-cycle threshold values — or the limit on the number of cycles a sample goes through during testing to detect the virus.

“PCR tests are very specific, and these are not false-positives,” he says. “The test is doing what it was designed to do — detect the viral RNA in samples.”

The article went on to explain how positive results at high-cycle threshold values could point to different levels of infectiousness in some cases. But in others, those results may be a consequence of the sample type and quality.

Read the full story.