CDC acknowledges mixing up coronavirus testing data

CDC acknowledges mixing up coronavirus testing data
Image credit to Wikimedia Commons. Image modified from original.

The Centers for Disease Control and Prevention announced that it mistakenly combined the data of two different tests in the agency’s statistic for the Wuhan coronavirus, which gave rise to public doubt and concern within the medical and scientific community by inaccurately painting a picture of the state of the pandemic in the United States. 

The Centers for Disease Control fused the data of genetic tests that spot individuals who were infected, by utilizing a process known as P.C.R., Polymerase Chain Reaction, with results from serology testing, which searches for antibodies in the blood— the antibody testing is used to determine if people were previously infected.

The practice was first reported by Miami public radio station W.L.R.N., which was confirmed by the agency in a subsequent email to NPR.

From a nationwide analysis of COVID-19 data released this week, it shows broad discrepancies between what some states are reporting about testing for the novel coronavirus to the public, and what is being published by the C.D.C. The analysis lists Florida as “the most extreme case” of testing discrepancies between what the state and the federal government are reporting.

Asked about the discrepancy, the C.D.C. told W.L.R.N. that it is lumping together antibody tests along with tests for active COVID-19 infections, in an apparent conflation of its antibody testing definitions.

In John Hopkins Center for Health Security, an epidemiologist, Jennifer Nuzzo, displayed her worry that mixing the 2 types of tests could lead to the impression that more testing of active cases had been done. 

“Reporting both serology and viral tests under the same category is not appropriate, as these two types of tests are very different and tell us different things,” Nuzzo wrote in an email to NPR.

Serology tests don’t provide live data regarding the frequency of new infections occurring. And mixing the tests is problematic because it could leave businesses and governments with a pretense of the pandemic’s atmosphere. It’s crucial because sufficient testing is considered vital for keeping the epidemic monitored, especially as the nations begin to loosen social distancing measures.

“Only PCR tests can tell us who is infected and should be counted as a case,” Nuzzo wrote. “The goal for tracking testing is to understand whether we are casting a wide enough net to identify cases, and only viral tests can tell us that.”

Additionally, confusing antibody testing with diagnostic testing could lower the number of tests that produce positive results, reducing the overall positivity rate. It’s another critical benchmark. The World Health Organization has endorsed a positivity rate of 10% or less to determine whether enough testing is taking place.

“I suspect it will artificially lower the percent positive,” wrote Caitlin Rivers, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health, in another email to NPR about the C.D.C. testing data.

C.D.C. spokeswoman Kristen Nordlund wrote in an email to NPR that the “majority of the data is PCR testing” but acknowledged that the agency’s tally includes antibody testing because “some states are including serology data” in their testing numbers.

“Those numbers still give us an idea of the burden of COVID-19,” Nordlund wrote.

She added, however: “We hope to have the testing data broken down between PCR and serology testing in the coming weeks as well.”

Numerous states have acknowledged that they are combining both types of testing in recent weeks, but at least, in Virginia, they reversed that practice after the information publicly surfaced.

The critique over how testing results are being reported is the most recent controversy relative to testing for the new virus. 

Countless health specialists have criticized the federal government for failing to ramp up testing quickly to track and control the epidemic.

The C.D.C. acquires testing data from different sources, including hospitals, commercial testing companies, and state public health labs. At the same time, officials have been working to develop standardized criteria to alleviate complaints about the confusion about reporting requirements.