Cape public health director 'surprised' at CDC antibody caution

The director of the Cape Girardeau County Public Health Center is “a little surprised” at new guidance this week from the Centers for Disease Control and Prevention (CDC) about coronavirus antibody testing.

“(CDC) recommendations of two weeks ago can change,” said Jane Wernsman, director of the center.

Antibody tests used to determine whether people have been infected with COVID-19 might be wrong up to 50% of the time, the CDC reported Tuesday.

The tests, the CDC continued, are not accurate enough to make important policy decisions such as grouping people together in schools, dormitories or correctional facilities.

Wernsman said Phase One of the local antibody study, in which 1,842 specimens were collected, concluded May 15.

“We feel very comfortable with the testing we did (this month),” said Wernsman, who added the specificity results (true negatives) were at 99% and sensitivity tests (true positives) came in at 99.6% accurate for antibodies.

“It seems (the CDC) might be generalizing all areas,” said Wernsman, “but every site is different.

“We’ll review and consider (the CDC’s new guidance) as we move forward into Phase Two.”

The second phase of antibody testing in Cape Girardeau County, which is supposed to take place at least eight weeks after the initial round, will probably begin right after Independence Day.

“We’re probably looking at the week of July 6 to 10,” Wernsman said.

The health center is partnering with SoutheastHEALTH for the antibody study.

Wernsman admitted there remain “a lot of unknowns” with the coronavirus.

“Information we have today may be different tomorrow,” she said, “but hopefully we’re getting closer (to solutions).”

In its updated guidelines, the CDC report states, “It cannot be assumed that individuals with truly positive antibody test results are protected from future infection.”

The Food and Drug Administration also has cautioned about relying too heavily on the reported accuracy of antibody testing.

Antibodies are collected through blood draws. Commercial laboratories tend to refer to “antibody” testing while clinicians and medical researchers prefer the term “serology” testing.