Beginning Tuesday, American Esoteric Laboratories in Memphis will begin processing blood samples to see if people who have recovered from COVID-19 have developed the antibodies that may give them immunity.

Physicians and researchers have been waiting for the test to be available, saying it will allow them to find out who is safe to treat homebound patients, for instance, and who can potentially return to work in the public sphere.

“This test tells the doctor and the patient whether they have had COVID-19 based on the antibodies,” said Dr. Manoj Jain, infectious disease expert advising the Memphis/Shelby County COVID-19 Task Force.

“If the patients have antibodies to COVID-19, then there is a high likelihood they had the infection and would be immune to repeat infection. We do not know that for certain, but we suspect so.”

The first tests will be samples to program the lab’s computers. It could be a few days before AEL is accepting clinical samples.

“AEL is coordinating with hospitals, public health and other medical officials to determine the best utilization of the testing and how it will be used for ‘return-to-work’ efforts,” AEL said in a statement late Monday. 

The lab has the capacity to run 3,000 blood samples a day.

As early as June, thousands of people a day could be getting the antibody blood test in outpatient clinics across the city as officials drill down to see what percentage of the population has immunity, said Dr. Jon McCullers, associate dean of the College of Medicine at University of Tennessee Health Science Center and chief pediatrician at Le Bonheur Children’s Hospital.

“I want to test every health care worker in the Memphis region – that’s 40,000 people. I also want to test every first responder, police, firefighter and EMT in the region. We also need to test the general public broadly. I’d love to see 10-20% of the general public tested.”

From June to September, McCullers envisions a public campaign to test 200,000 people for antibodies to coronavirus. He thinks it’s possible a second round will be necessary three to six months later.

Researchers are optimistic that people who survive the novel coronavirus will develop antibodies to the virus because that was the case with SARS, or severe acute respiratory syndrome, which is a cousin virus. With SARS, survivors had immunity for about nine months before their resilience began to wane.

“We are hoping this follows a similar path,” Jain said. “But, we are not sure.”

Friday, the World Health Organization warned there is no evidence that a blood-plasma test can show who develops immunity and is no longer at risk of infection.

While the antibody test is a breakthrough, experts say no single test or practice is more important than the mix of testing, hand-washing, social distancing and contact tracing.

As of Sunday, 3,299 people had been identified as contacts with people who have tested positive in Shelby County; 1,247 were still in quarantine, according to data shared with the Memphis/Shelby County COVID-19 Task Force.

“Hopefully, treatment and a vaccine will be in the pipeline,” Jain said, noting the antibody test gives “perspective on where we are.” 

If the nasal-swab, or PCR, test shows a snapshot of who is positive at a given time, the antibody test “gives us a view of what has happened in preceding weeks. That can be very important,” said Dr. Stephen Threlkeld, infectious disease expert treating COVID-19 patients at Baptist Memorial Hospital-Memphis.

“It’s the combination of the two that affords us the most information.”

The PCR – polymerase chain reaction – test is used to make copies of a DNA sample rapidly.

As a family, the coronavirus has multiple lines, including mild strains that cause the common cold.

“You have to be careful to make sure that one antibody doesn’t cross-react with another,” Threlkeld said. “It could make the test look positive SARS-CoV-2 by mistake.”

COVID-19 is caused by the virus SARS-CoV-2.

Threlkeld worked with AEL on the accuracy of its test.

“Preliminarily, it looks like a very good test. It seems to be very specific for these antibodies. We hope that will minimize false positives.”

While McCullers agrees it’s important that a local lab has a test, he says the bulk of tests in Memphis will not go through AEL, which is a commercial laboratory.

“Some people are going to be able to start getting (the antibody test) now though AEL, but the process I am talking about ... will have to wait until we have capacity to do large-scale testing, thousands and thousands of tests a day, which we probably are not going to have until June.”

That, he says, may be a smarter time frame for antibody testing, which he calls a late-stage test.

“Right now, if you look at other places around the world that have looked at this, 1-2% have immunity,” he said. “It may be more helpful to wait until we’ve been through this entire first wave (of infection), and then we test every health-care worker – all 40,000 of them – and get a good snapshot at that point of who is immune.”

Eventually, there will be a vaccine which should make everyone immune, Threlkeld says.

“But, it’s yet to be seen whether or not we would need a booster shot like we get with influenza. And there still are some uncertainties in how antibody testing will go. Some with milder disease, for example, may not develop as large or robust of an antibody response. And it may be harder to pick up on tests,” he said.

Threlkeld says to expect a variety of antibody tests, including some that will be performed in doctors’ offices and others in laboratories.

“The problem, when you release a lot of different types of tests at once, you really have to be careful those tests have been studied adequately,” he said. “You have to pay close attention to what the specificity and sensitivity of those tests are. The faster a test comes out, the less opportunity there has been to study that test.”

Baptist, which has been treating COVID-19 patients for several weeks with antibody infusions, is receiving calls from people who have recovered and want to donate plasma.

“It’s gratifying. It’s encouraging,” Threlkeld said. “We have been able to accommodate quite a few. We are looking at the cases we know were positive and making sure they have a follow-up test that is negative in trying to get them into the system to donate plasma.”

If Baptist does not have proof the person tested positive, it cannot accept the donation “until we have more direct advice from FDA about antibody tests that are coming soon,” Threlkeld said.

Baptist intends to give the antibody test to a “large proportion” of its employees and patients, potentially beginning this week.

“That is how you gain safety for both health care workers and patients,” he said.

Because the antibody test shows who was sick a month ago, McCullers says it doesn’t matter “if the test is done today or in July.

“If we make some different rules for the next wave, if you are immune, you get a certificate or something. Now, you can work in a restaurant and not wear a mask. These are the things you will want to know if you are immune,” McCullers said.

If Medicare and Medicaid elect to pay for antibody testing, everyone who gets tested will be reimbursed, McCullers said.

“Anybody who can do phlebotomy, any out-patient clinic in the city, could test” for antibodies, McCullers said. “We won’t have to worry about all this PPE and special items like we do for Tiger Lane because these aren’t going to be infectious patients. It becomes a very different sort of thing than what we are trying to deal with today where we are worried about infections.”

UTHSC is offering a free Zoom session, “The Role of Laboratory Testing in the COVID-19 Pandemic,” from 11 a.m. to 12:30 p.m. Wednesday, April 22.

It will feature a panel of laboratory science experts speaking on the role of testing in the pandemic. To participate, go here.