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What’s the Latest on Coronavirus Antibody Tests?

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Published on June 2, 2020

What type of tests are available for the coronavirus? How reliable are they? If I want to get tested, what do I need to know?   

In Part 1 of this Answers Now program, host Andrew Schorr talks to noted laboratory science experts Dr. Susan Leclair and Dr. Jim Griffith, from the UMass Center for Molecular Diagnostics. They explain what an antibody is and if your cancer will interfere with the test results. They also discuss what questions you should ask before getting tested. Watch now for expert advice on COVID-19. 

For Part 2 of this conversation, watch Your Coronavirus Test Questions Answered

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Transcript | What’s the Latest on Coronavirus Antibody Tests?

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you.

Recorded on May 27, 2020

Andrew Schorr:

Greetings from San Diego County, USA. Good morning, good afternoon, good evening, wherever you are. I'm Andrew Schorr. I am so excited about this program, because I am totally confused about testing for the coronavirus antibodies. I'm not sure what to make of it, how to make decisions, what to get or not get. So let's be joined by our experts. So here comes Dr. Jim Griffith who joins us from Dartmouth, Massachusetts, three miles north of, or excuse me, 30 miles away from Providence, Rhode Island, and about 60 miles below Boston, and his wife who is also a noted laboratory science expert, Dr. Susan Leclair. So first of all, good morning, Jim, and good morning, Susan. Thanks for being with us once again.

So, Susan, let's start with you. There are two kinds of, two groups of tests, right? There is a test for the virus, and a test for whether you have it now or whether you've had it. So maybe decipher that for us, because I think people are really confused.

Dr. Leclair:

The test that is done from the nasal swab or the throat swab are tests for do you have the antigen, the virus now, at this moment? Because what they're trying to do is take cells from those two areas that contain the virus and test for the virus. The antibody tests are asking, did you anywhere between a week-and-a-half to maybe three or four months ago have this antigen or virus? That virus is long gone, but what you still have is the defense you made against it. So the antibody test is a test for did you have it before? The antigen test is do you have it now?

Andrew Schorr:

Okay. Jim, so let's talk about the reliability of tests. So it doesn't do me any good if it's a false positive, false negative. I don't know what I make of it, or my doctor. Could you talk a little bit about, I know these terms come up, sensitivity and specificity? Does that relate to just the test, do you have the virus? And about how many tests are out there, and how we can get a reliable one?

Dr. Griffith:

Okay. Well, first of all, there are, because of the notoriety of this disease worldwide, there are literally hundreds of tests, at least 200 that have been described in the scientific literature. All tests, no matter what, they could be your glucose test or your cholesterol test, all tests have sensitivity and specificity. Sensitivity for any test is, if the thing the test is looking for is there, does the test find it, okay? So if the stuff is there, does the test come up positive? When that doesn't work, that's called a false negative. Specificity on the other hand is, does the test find anything other than what it's looking for? So, if it's a test for cholesterol, does the test go off when it finds glucose? So when that happens, that's a false positive. So sensitivity, is the stuff is there, does it find it? Specificity, does it find anything it's not supposed to find?            

Andrew Schorr:

All right. So the FDA through sort of emergency authorization, authorized some, but there are more tests out there than were authorized by the FDA. So first of all, how do we get the good stuff, if you will?

Dr. Griffith:

Well, you could try to ask your physician or nurse practitioner or whoever you're interacting with to get a test if you're thinking of getting a test if they know what the sensitivity and specificity of the test is. Generally, in clinical laboratory science a good test is 95 percent and 95 percent, something like that. The first emergency use authorization test for coronavirus was a test made by Abbott Diagnostics and it had, and still does, somewhere between 15 and 40 percent false negatives. So that's not so good. That is, to a clinical laboratory scientist, that's pretty close to useless. On the other hand, there was a test that came up more recently that is close to 100 percent. It's 100 percent for specificity and 98 percent for sensitivity, and that's a test by Roche Diagnostics. And I'm only mentioning two that are on opposite ends of the scale here, but as a patient you surely can ask, before I have this test done to see if it makes any sense to me, “Do you know what the sensitivity and specificity is?” And that's a reasonable question to ask, and you should expect to get an answer.

Andrew Schorr:

Okay. Susan, as you know, many, most in our audience are people with cancer, like me, I have two blood cancers, chronic lymphocytic leukemia, myelofibrosis. Somebody else may have their immune system affected even by chemo or treatment for a solid tumor, whatever, okay? And so we say okay, “Well, will the test result be affected by our status?”

Dr. Leclair:

If you're talking the antigen tests, particularly…

Andrew Schorr:

…snapshot.

Dr. Leclair:

The snapshot, particularly the really good ones, the answer is no, because for the most part the antigen test is looking for the presence of the virus. So it doesn't matter that you have or have not got an adequate response to it. That test is the one that is looking for the virus. It's a totally different kettle of fish if you're looking for the antibody test, because then we have to know—or at least guess—how good your immune system is and how functional that is.

Andrew Schorr:

Okay. Let's go on to that, Dr. Leclair. People are writing in questions, say okay let's start with the basics. What's an antibody?

Dr. Leclair:

Okay, an antibody, and here's just a skeleton schematic of it, really does look like a double Y. It's got a bottom tail that you think of in terms of a Y, and a fork up at the top. The bottom part and most of the top stays the same throughout your life, but that piece at the top on this graphic shows you that that's what changes and differentiates like an anti-smallpox antibody from an anti-measles antibody, from in this case an anti-COVID-19 antibody. You need to be able to make an antibody. You need to be able to make them in enough quantity to attack your antigen that you're looking at, again COVID in this one. And you have to make sure, or at least your immune system has to make sure that it keeps that amount of antibodies at a level sufficient to protect you if it is a protective antibody.         

You have heard tons of people I think talk about the fact that we don't know whether these antibodies are protective or not. Here's an example. Because I was lucky, back in the day I had measles, all by myself. That ruined one summer for me in a hurry, and to this day if you were to test my antibodies against measles, I would get a response, because those antibodies remember and are annoyed about it to the point where they stayed functional for a number of years. On the other hand, I could have had a cold November of 2019—when you could have a cold and not panic about anything. And other than weeping and wailing and carrying on for two weeks, my immune system responded, it made antibodies, it got rid of my cold, life was wonderful. Except the cells that make those antibodies stopped making them about January, February. So could I get that cold again now? Yes, because the antibodies that I made got rid of the first cold, but they're not protective in the sense they don't stay longer.

Andrew Schorr:

So, Jim, we're hearing about antibody testing. First of all, it's looking to see whether as we said, in the rear view mirror your body has produced this defense or responded to the assault of the virus previously, okay? So if you have that, are you protected? Or for how long? I mean, Susan was just talking about that. Measles, yes, forever or a long time. Cold, maybe not. So what about with COVID-19?

Dr. Griffith:

Well, this COVID-19 is a coronavirus, and I will mention that four of the 200 viruses that cause the common cold are also coronaviruses, and typically when you have a coronavirus cold caused by one of those four, you do make antibodies but not very many. And they eventually are protective maybe for a couple of weeks, maybe a little bit longer. So what we don't know about this guy, because he's different, is how many antibodies you're going to make, and for how long they will be there. And then the third part is will they do anything? We have no idea if antibodies, if you make an antibody response, we have no idea if those antibodies will be protective.

Andrew Schorr:

So first of all, Jim, you talked about the sensitivity and specificity and you said it relates to any test. So that would be the same with antibody tests too, right?

Dr. Griffith:

Correct.

Andrew Schorr:

Sensitivity and specificity. Okay, so will the antibody test then be different for somebody who wasn't very sick, will the result in somebody who was very sick? And I'll give you an example. A few weeks ago, we had on one of our favorite myeloma doctors, Noopur Raje from Boston, not too far from you. She had had COVID. Her husband did too, a physician. She didn't get very sick. He got very sick and was in the ICU. Fortunately, they're both doing well is my understanding. She had an antibody test, didn't show much, but she'd had the COVID. And he had showed a lot. So this variability in the response, what does it relate to, Jim?

Dr. Griffith:

Well, it could, what you just described in those two patients, could also relate to their different immune systems. They're different people. They may respond differently. There is, just on the general level, for sure if you have a massive invasion as the husband did, if you have a massive invasion of, in this case these viruses, your immune system should be fully alerted. And you then should, according to the central dogma of immunology, you should then make a massive response, because you are having a massive invasion. Her case, maybe she didn't have such a massive invasion, so she might not have made such a massive response.

Andrew Schorr:

So, Jim, we're all sitting here wondering, well okay, if we get an antibody test, a reliable one, how protected should we feel?

Dr. Griffith:

Well, if you have a good test like the new Roche one that just came out, that indicates that you have antibodies. You still don't know if the antibodies are protective, so I certainly wouldn't think that I'm bulletproof if I had a good test, and it came out positive. Therefore, I would feel good about it, better than the opposite side—we will eventually know, but right now we don't know.

Andrew Schorr:

And that's a fair answer, and that's why we keep doing these programs, Answers Now, because the “now” is the operative phrase right now.

Editor’s Note: This is part 1 of 2 programs.

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you.

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