Getting An Antibody Test For The Coronavirus? Here's What It Won't Tell You

May 21, 2020
Originally published on May 21, 2020 6:42 pm

Salvador Perez got really sick in April. He's 53 and spent weeks isolated in his room in his family's Chicago apartment, suffering through burning fevers, shivering chills, intense chest pain and other symptoms of COVID-19.

"This has been one of the worst experiences of his life," says Perez's daughter, Sheila, who translated from Spanish to English for an interview with NPR. "He didn't think he was going to make it."

Perez recovered and now wants to go back to work as a chef at a Chinese restaurant. But his boss told him he needs a test — an antibody test — first. So he found a place to get one and tested positive. His blood indeed has antibodies to the novel coronavirus — proteins that his immune system produced when it fought off the pathogen.

"He feels great that he can get ... back to work, since we haven't really paid our bills," Sheila Perez says. "And he feels great that he can start doing what he did before the virus again."

But her father is also nervous. His doctor told him the antibodies might give him some protection against catching the virus again but also stressed that's far from guaranteed.

Salvador Perez became sick with symptoms of COVID-19 in April and spent weeks self-isolating at home in Chicago. When he recovered, his employer asked him to take an antibody test before he'd be allowed to return to work.
Sheila Perez

"He's anxious that he doesn't want to get sick. He's kind of scared of going back to work because ... he might go through it again," his daughter says.

Salvador Perez is right to be worried. It's still not certain that antibodies measured by such a test would protect him from catching the virus again. And if the antibodies are protective, it's unknown how strong that protection might be or how long it might last. There are also questions about the reliability of many antibody tests being sold.

Researchers are urgently trying to answer those uncertainties and figure how best to conduct antibody testing.

Nevertheless, increasing numbers of people are getting the tests — many without recognizing how much is still unknown about what the results mean.

Some employers, such as Perez's restaurant, are requiring workers to take antibody tests if they want to continue working or return to their jobs. Others are getting employees tested to see how widely the virus has spread through their workforce and to try to find ways to improve worker safety. And some labor unions are helping workers get tested in hopes of offering them some sense of security against the virus.

In addition, some individuals are buying the tests themselves out of curiosity and to use as a basis for personal decisions, such as whether it's safe to start spending more time with close friends and extended family members who are outside the household.

But the idea of using antibody testing in these ways worries many doctors and public health authorities because there are many common misconceptions.

For starters, the antibody tests are only a sign of past infection. Whether the infection is actually gone can only be determined by a diagnostic test that identifies genetic material from the virus or viral particles.

Some people also falsely think testing positive on an antibody test proves they can't get infected with the virus again.

"I think people just want this to go away and want to resume their normal lives," says Kelly Wroblewski, director of infectious disease for the Association of Public Health Laboratories. "But my fear is [antibody tests are] going to be used as this sort of golden ticket to demonstrate immunity — when we just don't know if that's the case."

Still, Wroblewski and others acknowledge the results might offer at least some useful guidance in certain cases.

"If I had a household where I had a number of younger individuals in the household, one of whom had antibodies, I think that that individual would probably be the safest bet to be able to safely go to get the groceries," says Michael Mina, an assistant professor of immunology and infectious disease at the Harvard T.H. Chan School of Public Health.

But, Mina quickly adds, "I still wouldn't want that individual going to get groceries and then going the next day to a nursing home to see Grandma." Having antibodies against the coronavirus is just no guarantee that you won't pick up or pass along an infection, he says.

Still, antibody testing could provide researchers with valuable information for studying overall trends in the epidemic, such as how many people in the community have actually been exposed to the virus. Antibody testing could also help identify people who could donate blood plasma containing antibodies; such plasma is being investigated for possible treatments for COVID-19 patients.

Immunologist Juanita Mora has been arranging antibody testing in Chicago for people who need the test to go back to work. A positive test doesn't guarantee immunity from coronavirus reinfection, she tells her patients. Social distancing and other precautions are still important.
Juanita Mora

Dr. Juanita Mora, an immunologist at the Chicago Allergy Center, helped Perez and his family get tested with one of the tests that's at least been approved for use by the Food and Drug Administration. (The agency recently cracked down on unregulated tests.) Mora has been doing the same for an increasing number of people in Chicago's Latino community who are being required to get antibody testing by their employers.

"They want to go back to work and feed their families," Mora says. "They need the money."

She says she makes sure her patients understand that they still have to be careful and can't let down their guard just because they get positive results on an antibody test.

"Having positive antibodies may mean that you have some protection, but you can still get it again," Mora tells her patients. "And then you want to protect your loved ones, right? So you want to teach your kids the right thing to do.

"So, keep the face cloth on. Keep the social distancing, and so forth," Mora advises her patients.

But people are not just getting antibody tests to go back to the workplace.

Jon Pepper and his wife, Diane, who live in New York City, had been wondering whether they had COVID-19 ever since they got sick in April. He's 64, and they've simply wondered whether they might now have some immunity to the virus. He decided to get a $119 antibody test directly from Quest Diagnostics, a big commercial laboratory that now sells the test to anyone who wants one. Diane Pepper was soon tested, too.

"The reality is people are going to be scrambling to get testing," says Dr. Jay Wohlgemuth, Quest's senior vice president and chief medical officer. "They're going to get any testing they can get their hands on. We see this is a responsible way to get testing." The company says it's a responsible provider — it makes sure a doctor explains the results.

Jon Pepper and his wife, Diane, live in New York City. They took an antibody test after recovering from an undiagnosed illness in April to confirm their suspicions that they'd had COVID-19.
Jon Pepper

The Peppers say testing positive on the antibody test gave them peace of mind.

"I feel like we have some level of protection that our bodies have have been through this, and they're fighting back," Jon Pepper says. "And they have the capacity to fight back further if necessary.

"So I think it's something that's in my corner in getting through this," he adds, "and especially in a hot spot like New York City, where we're surrounded by people who have been exposed to this and infected."

Pepper says he and his wife are still being cautious. They stay at least 6 feet away from other people when they go outside. And they're wearing masks when they go shopping. But Pepper and his wife are now thinking about having their adult children over for dinner for the first time in months.

"At some point we have to resume life again. And based on this test I feel like we have some sense — a bit of security," Pepper says.

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MARY LOUISE KELLY, HOST:

As the nation tries to reopen, more and more people are getting tested to see if they have antibodies in their blood that might protect them against the coronavirus. But do those antibodies equal protection? NPR health correspondent Rob Stein has been looking into this.

ROB STEIN, BYLINE: Salvador Perez (ph) is 53 and lives in Chicago. He got really sick in April with COVID-19 - burning fever, shivering chills. I talked with Perez with one of his daughters, Sheila (ph), so she could translate for us.

SALVADOR PEREZ: (Speaking Spanish).

SHEILA: He said this has been one of his worst experience of his life. And he thought he wasn't going to make it.

STEIN: Perez isolated himself in his room in their apartment while he was sick to protect his family. But now Perez wants to go back to work at a Chinese restaurant. But the restaurant told him he needs a test, an antibody test, first. So he found one and tested positive. He has antibodies to the coronavirus, proteins that his immune system produced to fight the virus.

PEREZ: (Speaking Spanish).

SHEILA: He says he feels great that he can move back to work since we haven't really paid our bills yet. And he feels great that he could start doing what he has done before the virus again.

STEIN: But he's also nervous that he might get exposed to the virus again at the restaurant.

PEREZ: (Speaking Spanish).

SHEILA: He's anxious that he doesn't want to get sick. He's kind of scared of going back to work because he doesn't want like - or gets a little worried that he might go through it again.

STEIN: And Perez is right to be worried. Those antibodies might help protect him, but they might not or they might only protect him a little or just for a little while. No one knows. And there's lots of questions about the reliability of a lot of the antibody tests out there, but lots of people are getting the test anyway. Dr. Juanita Mora is an immunologist helping Chicago's Latino community get antibody tests.

JUANITA MORA: I had a gentleman this morning, and he came in because he wanted to do antibody testing because there had been three co-workers who had passed away from COVID-19 and there were over 200 cases of COVID-19 positive in their factory. And so prior to getting back into work, his job was requiring him to get this test done.

STEIN: But Mora says she tries to make sure all her patients understand that they still have to be careful. No one can let down their guard just because they have the antibodies.

MORA: You having positive antibodies means that you have some protection, but you can still get it again. And then you want to protect your loved ones, right? So you want to teach your kids the right thing to do. So keep the face cloth on. Keep the social distancing and so forth. Like, thank God you're able to go back to work, et cetera, but this is the only way that we can control this pandemic some.

STEIN: But people are not just getting antibody tests because they have to for work. Some employers are doing antibody testing to figure out how many employees have been exposed to the virus and where. Some labor unions are offering the test to workers to give them some sense of security. And for $119, anyone can now get one through big commercial testing companies like Quest. John Pepper and his wife Diane have been wondering whether they had COVID ever since they got sick in April, too, and whether they might now have some immunity, so they got tested.

JOHN PEPPER: I feel like we have some level of protection, that our bodies have been through this and they're fighting back and they have the capacity to fight back further if necessary. So I think it's something that's in my corner in getting through this and especially in a hot spot like New York City where we're surrounded by people who've been exposed to this and infected. And it's a bit of peace of mind for me.

STEIN: Pepper, who's 64, says they still try to stay 6 feet away from other people, wear masks when they go into stores, though mostly to put other shoppers at ease. But behind those masks, Pepper and his wife feel more relaxed, and they're thinking about having their adult children over for dinner for the first time since New York's lockdown started.

PEPPER: At some point, we have to resume life again. And based on this test, I feel like we have some sense of a bit of security.

STEIN: But all this makes many doctors and public health experts very nervous. There's a lot of misconceptions about antibody tests, like antibodies mean you aren't infected anymore - you might be. Or antibodies mean you can't catch the virus again - maybe you could. So it would be dangerous to, say, stop wearing a mask, visit your elderly parents, get too close to other people at work or anywhere else. Kelly Wroblewski is director of infectious diseases at the Association of Public Health Laboratories.

KELLY WROBLEWSKI: I think people just want this to go away and want to resume their normal lives. And I want this to go away and I want to resume my normal life. But my fear is that they were going to be used as this sort of golden ticket to demonstrate immunity when we just don't know that that's the case.

STEIN: That said, Wroblewski and others say an antibody test might offer at least some guidance if someone in the family has to go to the pharmacy or back to work. Here's Michael Mina. He's an infectious disease expert at Harvard.

MICHAEL MINA: If I had a household where I had a number of younger individuals in the household and one of whom had antibodies, I think that that individual would probably be the safest bet to be able to safely go and get the groceries. I still probably wouldn't want that person going getting groceries and then the next day going to a nursing home to see Grandma.

STEIN: So no test yet offers some kind of golden immunity passport guaranteeing it's safe to roam the world freely again. But more and more people are starting to use antibody tests to make important decisions about how to try to reemerge back into their lives.

Rob Stein, NPR News. Transcript provided by NPR, Copyright NPR.