90 Percent of Positive COVID-19 Tests Could Be Inactive

North Carolina’s positive cases of COVID-19 might be misleading, according to a recent article from WRAL. After the John Locke Foundation’s Director of Regulatory Studies, Jon Sanders, sounded the alarm about North Carolina’s polymerase chain reaction (PCR) testing at the beginning of the month, the attention PCR testing has received has only grown. WRAL writes:

Polymerase chain reaction, or PCR, tests involve rapidly making millions to billions of copies of a specific DNA sample through a process called cycling, amplifying it enough to study in detail…

For its coronavirus test, North Carolina’s state public health lab cycles a DNA sample up to 37 times before deciding whether it’s positive or negative. LabCorp, the main private tester in the state, has a cycle threshold that’s even higher, at 38…

The higher thresholds raise questions when people are labeled as positive, he said, noting the test could detect inactive virus.

Cycle thresholds of these numbers could be vastly overestimating the number of active cases. WRAL writes:

Dr. Michael Mina, an assistant professor of epidemiology at Harvard University’s T.H. Chan School of Public Health, has recommended cutting off the cycle threshold closer to 30 to identify only those people who have enough virus to spread. Lowering the cycle threshold would reduce cases by 80 to 90 percent, he said.

Heneghan said thresholds in the high 30s paint a false picture, causing unnecessary quarantines and negative economic impacts.

However, some health officials see no issue with the high cycle threshold, claiming “better safe than sorry” with COVID-19 tests. WRAL writes:

Scott Shone, director of the state’s public health lab, said the debate misses the point of the testing.

“These tests weren’t designed specifically to identify how much virus is there, just whether it’s there or not,” Shone said… adding that it’s better to have testing that’s too sensitive because a false positive is better than a false negative, which could lead to more spread.

Read WRAL’s full piece here. Read more about PCR testing from JLF’s Jon Sanders here and here.