As private laboratories grouped the results of two types of COVID-19 tests, daily reports from the Department of Health and Environmental Control of SC to the public gave a more optimistic picture for months of the amount of tests being conducted in South Carolina than was the case. case .
DHEC found that private laboratories have sent total diagnostic and antibody tests together. Although diagnostic tests can determine whether someone has an active COVID-19 infection, antibody tests cannot. The difference does not affect the number of confirmed cases of coronavirus disease in South Carolina.
Antibody tests are useful because they show whether someone has been exposed to the virus before, although Dr. Joan Duwve, director of public health at DHEC, says yes “full of many uncertainties.”
The health department discovered the problem in late May, said Nick Davidson, who leads DHEC’s COVID-19 response team. She has been reporting numbers that way since the beginning of March. As a result, an important metric in the department’s reports – the percentage of tests that tested positive – was artificially low.
If someone received a positive result on the antibody test, they were not included in the daily total of cases, the agency said on Thursday. To date, DHEC has reported 265,361 tests. Thursday’s announcement revealed for the first time that about 10 percent of these are antibody tests.
A positive percentage above 10% is cause for concern because there are not enough tests being done, said Jennifer Nuzzo, an academic at the Johns Hopkins Center for Health Safety.
South Carolina has now reported a positive percentage above 10% for three consecutive days.
Duwve said the result was a “slight increase” in the percentage of reported positives.
“The percentage rates of positivity in the past week or so were high, mostly above 10 percent,” she said. “What this tells us is that we are seeing a real increase in activity, and the numbers also indicate that.”
Hospitalizations due to COVID-19 are also increasing, she said.
Moving forward, DHEC has committed to separating the two types of tests in the total it reports every day.
Reach Mary Katherine Wildeman at 843-607-4312. Follow her on Twitter @mkwildeman.