Coronavirus data used in decision to reopen Georgia flawed

ATLANTA (AP) — Data on coronavirus infections that was a key driver in Georgia Gov. Brian Kemp’s aggressive push to reopen the state was flawed and may have distorted perceptions of progress against the virus.

Georgia Department of Public Health spokeswoman Nancy Nydam said in an emailed statement Thursday that the department included antibody tests when calculating the total number of tests conducted “since early April," using the same methodology as the Centers for Disease Control and Prevention. She said about 57,000 of the 407,000 total tests reported to the state have been antibody tests.

The inclusion of antibody tests in state testing data was first reported by the Columbus Ledger-Enquirer.

Antibody tests look for the presence of a protein that the body makes in reaction to the virus, while other, more common tests, called viral tests, look for the virus itself.

Conflating the two tests can create confusion about the current impact of the virus, said Dr. Richard Rothenberg, an infectious disease expert at Georgia State University. That’s because antibody tests tell you whether a person had the coronavirus in the past, not whether the person was infected at the time of the test.

Combining them can create “a false impression of what is happening now,” he said. He also noted that antibody tests made up about 15% of the total tests reported to the state — a figure that he said would make a “substantial impact” on the perception of the outbreak.

Antibody tests also tend to have lower rates of positive outcomes right now because they are being administered to a wide group of people, not just people suspected of being infected, said Benjamin Lopman, an epidemiologist at Emory University’s Rollins School of Public Health. So adding them to the testing numbers will “lower the percent positive in...