Christus doctors further explain antibody testing

Stacey Tinsley | Bossier Press-Tribune

Christus Health hospitals will be the first in the area to offer rapid antibody testing as part of an effort to more widely screen for people infected with the coronavirus.

The “COVID-19 IgG/IgM Rapid Diagnostic Test Kit” was unveiled by Christus Health on Tuesday. 

Christus Health will first begin using the test on associates and caregivers on the front lines. The rapid screening tool will also be used on hospitalized patients that the clinical team believes may have been infected with COVID-19 as well as patients who are scheduled for an urgent surgery.

There are currently 20,000 kits available to all hospitals in the Christus Health system and they are in the process of getting more.

Dr. Dave Benner, Christus Health vice president of clinical ancillary services, said they are not charging in an attempt to build confidence that this testing will get the hospital back to non-COVID health care.

Antibody testing could help identify asymptomatic people who never knew they had the virus or those with milder symptoms. Already, Christus officials said, the tests have flagged antibodies in health care workers who had been sick several weeks earlier but had not been tested at the time.

It is presumed that people who have antibodies — proteins produced to fight viruses and bacteria — for the coronavirus in their blood would have some level of immunity to the virus. But it remains unclear to what extent or for how long.

Still, some health experts anticipate such testing could allow for some easing of lockdowns and allow people who were previously infected to return to work and daily life.

“Those individuals are going to feel more and more confident about re-entering society and going back to normal,” said Dr. Sam Bagchi, chief clinical officer for Christus.

“I think we have flattened the curve for COVID. We have not flattened the curve for breast cancer, coronary artery disease, diabetes, all the other conditions out in our community that are not being treated because a lot of the traditional health care services are shut down or being avoided by people worried about social distancing,” Bagchi added.

Although the focus of the antibody testing will initially remain on Christus hospitals, Bagchi said the system is considering the possibility of partnering with communities down the line to assist businesses in reopening.

Because the antibody tests have not yet received federal approval as diagnostic tools, the hospital system is using them for screening purposes and pairing them with traditional COVID-19 laboratory testing — polymerase chain reaction tests — for verification.

“Our philosophy is both types of testing, the rapid PCR and rapid antibody testing, will be important in order for us to really understand where the virus is in our communities and where the virus potentially is in our facilities,” Bagchi said. 

He added that people found to have coronavirus antibodies could be candidates for donating their blood plasma, which is being transfused into some of the sickest COVID-19 patients.

Initial testing is being conducted on Christus health care workers and employees at its corporate offices in the Dallas-Fort Worth area. The system also plans to roll out the tests on hospitalized patients suspected of having COVID-19, as well as those undergoing urgent surgery for unrelated conditions.

Antibody testing is not effective during the first three to five days of illness, Bagchi said, because the immune system is still building its response to the virus. After that, he said the test was accurate in identifying two types of antibodies — those generated earlier in the infection and those created later as part of a “robust immune response.”

While it’s not known how long that immune response could last with this coronavirus, studies on SARS patients, who were infected by another type of coronavirus, found that they had immunity for two to three years, Bagchi said.

On its own, the antibody test Christus is using has a false negative rate of about 10 percent, based on internal validation testing. When combined with traditional lab tests, it reaches 98 percent accuracy in identifying COVID-19, Benner said.

No test is 100 percent accurate, Bagchi said, noting that oral and nasal swabs for traditional COVID-19 testing can be taken improperly or simply miss where the virus is being harbored in the body. That testing is not effective if it is conducted too late, when the virus has already worked its way out of a person’s system.

But together, the tests have high accuracy and can be completed in less than an hour, he said.

The U.S. Food and Drug Administration (FDA) has approved Christus Health to administer the tests to patients, doctors, nurses and anyone in healthcare working with coronavirus patients. Hospital officials say they expect the FDA to allow these simple tests to be the definitive test by the end of the week.