While NC COVID cases spike, new CDC report says that number actually could be higher

A report from the Centers for Disease Control and Prevention shows that the Sofia coronavirus antigen test showed false negative results in about 60 percent of those with asymptomatic coronavirus cases.

The Sofia antigen test was the first to get emergency approval from the U.S. Food and Drug Administration, and is one of the types of antigen tests being used in North Carolina.

Rachel Roper, a researcher at East Carolina University's Department of Microbiology and Immunology, says that the error is likely because antigen tests are much less sensitive than PCR tests.

"The PCR test is the most sensitive and the most accurate for COVID diagnostics," she said. "When you start looking at the antigen tests and the rapid tests... Those are much less sensitive. There's no amplification that occurs."

These potential false negatives are worrisome due to the already known spikes in cases that are occurring, but also because any increase caused by holiday gatherings has likely only just begun to show itself in the numbers.

"You start seeing cases a week or 10 days after events," Dr. Roper explained. "And then you see hospitalizations a week or two after that really go up, and then you see deaths increasing after that."

With so many getting tested before traveling for holiday gatherings, possibly flawed negative tests could have given some a false sense of security.

"You cannot trust the antigen tests if you get a negative," Roper said. "You have to get a PCR test after that to make sure you really are negative."

Dr. Ronald Hughes, chief medical officer of Rural Health Group in Roanoke Rapids, noted, however, that the antigen tests are designed for people with COVID-19 symptoms and that many of the false negatives are among asymptomatic people.