Scientists Warn CDC Testing Data Could Create Misleading Picture Of Pandemic

The Centers for Disease Control and Prevention has acknowledged that it is mixing the results of two different kinds of tests in the agency's tally of testing for the coronavirus, raising concerns among some scientists that it could be creating an inaccurate picture of the state of the pandemic in the United States.

The CDC combines the results of genetic tests that spot people who are actively infected, mostly by using a process known as polymerase chain reaction, or PCR, with results from another, known as serology testing, which looks for antibodies in people's blood. Antibody testing is used to identify people who were previously infected.

The CDC's practice was first reported by Miami public radio station WLRN on Wednesday and was confirmed by the agency in a subsequent email to NPR.

Jennifer Nuzzo, an epidemiologist at the Johns Hopkins Center for Health Security, expressed concern that adding the two types of tests together could leave the impression that more testing of active cases had been conducted than was actually the case.