These two diagnostic testing giants aren't the only ones in the antibody testing business.

By Karen Pallarito
May 01, 2020
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If you had COVID-19 (or think you did), wouldn’t it be nice to know if your immune system produced infection-fighting antibodies against SARS-CoV-2, the virus that causes the illness—and that maybe, just maybe, your body is better prepared to defend itself against this villain next time around?

With large clinical laboratories, like Quest Diagnostics and LabCorp, and their partners expanding access to coronavirus antibody testing, it’s becoming easier for individuals to get these types of tests. In theory, the results might give you some comfort. In reality, scientists caution that antibody testing may provide consumers false hope; that the value of testing, at least right now, is quite limited.

But should they? What are the benefits and drawbacks of antibody testing?

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Quest and LabCorp are betting that knowledge is power

Quest’s new direct-to-consumer service is designed to make it easy for individuals to access quality testing. People can order the antibody tests for themselves—no doctor visit required. Upon review of each request, a licensed physician will submit the order “if appropriate,” the company explains. After purchasing the test (it’ll set you back $119, according the online portal), you can set up an appointment for a blood draw at one of Quest’s 2,200 patient service centers.

A Quest spokeswoman confirmed that the test is conducted on two different diagnostic testing “platforms” and that consumers do not choose which test is used. “It is sent to the lab and platform that will allow for the quickest turnaround time, which is typically one to two days,” she said in an email.

Jay Wohlgemuth, MD, senior vice president and chief medical officer of Secaucus, New Jersey-based Quest, stated in a news release that such testing “may identify people who have likely been exposed to COVID-19 and might have mounted an immune response to the virus.” As he puts it, “Our goal is to empower individuals and their physicians to make informed decisions about their risk of infection and of spreading the virus.”

Separately, LabCorp of Burlington, North Carolina, said it, too, has begun offering antibody testing for the virus that causes COVID-19. Patients need to have an order for the test from a doctor or health care provider, but there’s no up-front, out-of-pocket cost. A LabCorp spokesman said that reimbursement, pricing, and coverage for serological testing “are not yet determined.”

People can have their blood drawn at tens of thousands doctors’ offices or at LabCorp’s 2,000 sites, including LabCorp at Walgreens locations, the diagnostics company explained. The ordering provider will receive test results one to three days after the specimen is picked up, and patients can access results via the company’s mobile app, it said.

What antibody testing does and doesn’t reveal

Antibody testing can tell you whether your immune system made proteins to fight off the virus. As a result, these tests may have a role to play in safely returning Americans to work. Use of validated blood tests can help public health officials identify patterns of exposure to the virus in local populations, for example.

At this stage of the pandemic, though, no one knows for sure whether a positive antibody test means you’re safe from future infection. “The problem is we do not know what antibody titer is necessary in order to be protected,” IDSA board member Tina Q. Tan, MD, professor of pediatrics at Northwest University’s Feinberg School of Medicine noted during a recent media briefing. “Titer” refers to the concentration of antibodies in the blood.

We don’t know what level makes someone safe or how long such protection may last, added IDSA board member John B. Lynch, III, MD, associate professor in the Division of Allergy and Infectious Diseases at the University of Washington. “Is it weeks, is it months, is it years, is it forever?”

Imagine a scenario where someone clearly tests positive for the virus when they were acutely ill and later tests positive for antibodies to the virus. Five months down the road, if that person falls ill with COVID-19 and tests positive again for SAR-CoV-2—assuming the test is correct—“that would say those antibodies were not protective,” Katherine R. Spindler, PhD, professor of microbiology and immunology at the University of Michigan Medical School in Ann Arbor, tells Health.

Antibody testing could give consumers “a false sense of security,” she says. People might disregard protective measure like wearing a mask, washing their hands, or maintaining social distancing if they believe they have immunity.

“We don’t know whether the antibodies that individual A has produced that react on this test are protective compared to the antibodies that individual B might come up with,” adds Spindler. And, she says, for any individual, we don’t know whether having been infected with the novel coronavirus provides any immunity at all. That’s the hope, of course, but that’s something we’re not going to know for a while.

Do people with antibodies to SARS-CoV-2 develop long-term immunity to the novel coronavirus like they do with, say, measles or smallpox? Once you’ve had these diseases or been vaccinated against them, you won’t get them in the future. The same is not true of norovirus, the highly contagious bug that causes vomiting and diarrhea.

Some antibodies are protective, while others merely serve as markers of disease, David Grenache, PhD, president-elect of the American Association for Clinical Chemistry (AACC) and chief scientific officer of TriCore Reference Laboratories in Albuquerque, New Mexico, tells Health. People with HIV, for example, make antibodies, but those antibodies don’t clear the infection. Antibody testing serves as a tool for identifying the infection.

Because scientists don’t currently know whether developing antibodies to SARS-CoV-2 confers immunity, Grenache says the test is of very limited value to individuals. “What do you do with that information?  It doesn’t change your behavior because we don’t know if you’re immune or not.” At best, the test results might satisfy their curiosity, he says.

Or, adds Grenache, imagine if someone had a nasal swab test that confirmed COVID-19. Antibody testing would be completely useless, he says, “because you already know you had the disease.”

Don’t I need antibody testing to donate my blood plasma to sick coronavirus patients?

Antibody testing can, in fact, identify people who have recovered from COVID-19, meaning they could potentially donate their blood plasma to sick COVID-19 patients, says Grenache. However, blood banks and medical centers where blood donations are being collected for clinical trials of so-called convalescent therapy would likely perform their own testing.

“A direct-to-consumer test for antibodies would not be used by any medical authority to enroll or not enroll someone in that type of trial,” he says. “They would be performing their own test.”

Currently, the FDA does not require antibody testing to be considered as a donor. Under agency guidelines, a positive nasal swab test at the time of illness and complete resolution of symptoms at least 28 days before donation may be enough.

What if I just want to know if I had the novel coronavirus?

Antibody testing can tell you whether you had the infection in the past, and that is true whether you had symptoms at the time or you were asymptomatic, says Grenache. But antibody tests have not been validated for diagnostic purposes, explains the FDA, adding that “we do not expect that an antibody test can be shown to definitively diagnose or exclude COVID-19.”

If you want to know whether you are currently infected, you need to have a different type of test, often called a PCR test, that involves swabbing the throat or nasal passages or spitting in a cup.

But if you still want to get tested for antibodies, at least look for a reputable provider of testing. And make sure they're using a valid test. The market has been flooded with tests that haven't been reviewed by the FDA for emergency use. Grenache advises consumers to beware of any pop-up clinic that offers rapid finger-stick antibody testing using a drop of blood and device that looks a lot like a home pregnancy test. “I wouldn’t trust that at all,” he says.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDCWHO, and their local public health department as resources.

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