Why antibody tests, a crucial step toward overcoming COVID-19, are still unreliable | Miles O'Brien Productions

Why antibody tests, a crucial step toward overcoming COVID-19, are still unreliable

Testing, both for active cases of COVID-19 and for antibodies indicating prior exposure to the disease, will be critical to resuming economic activity. In addition, scientists are racing to develop therapies for people who do get infected — especially those who become seriously ill. PBS NewsHour science correspondent Miles O’Brien joins Judy Woodruff to discuss the latest on COVID-19 testing and treatment.


Judy Woodruff:

Now the latest information on treating COVID-19 and finding ways to tell who’s been infected. As plans grow to reopen the economy, one key prerequisite will be testing for antibodies to see who has already been exposed and theoretically safe from further infection.

There is now a flood of new tests on the market, but not without controversy.

We’re going to look at that, as well as something else, an antiviral drug that was just today approved for emergency use.

Our science correspondent, Miles O’Brien, is here to help us sort things out.

It is part of our regular look at the Leading Edge of science and research.

So, Miles, let’s first look at this drug that was approved today to treat COVID-19. What are we hearing about it?

Miles O’Brien:

Well, Judy, the drug is called remdesivir.

The first documented COVID-19 patient in the United States in the Seattle area in January was infused with it. And that patient, who at the time was failing fast, had pneumonia, had a very abrupt turnabout for the good, and was released from the hospital only a few days later.

Now, the details of the study announced today bear that anecdotal story out. It suggests that COVID-19 patients who are infused with remdesivir can be released as soon as four days earlier.

Now, the doctor who treated patient number one, Dr. George Diaz at the Providence Regional Medical Center in Everett, spoke to us just a little while ago. And he said this is making us more optimistic that we’re headed down the right path here with remdesivir.

Judy Woodruff:

But, Miles, this is not the end of it, more studies to be done. I mean, there’s a lot of work still being done on this drug, aren’t there?

Miles O’Brien:

It’s literally global. It’s a global study, multiple locations.

But now that there is news that the drug can, in fact, block the progress of the virus, it changes the rule of the study. It allows them to remove the placebo patients. In other words, everybody will now get the drug to see if there’s some effect.

We still don’t know if remdesivir changes the mortality rate, if fewer people die. That’s still under review. There was a study in China earlier on in this whole pandemic that involved that particular issue. But it didn’t come to any conclusion on that. It was a flawed study. Only half of the subjects that they wanted to test were involved in the study. And those subjects were sicker.

So it’s kind of a muddied study right now. So, there’s still more to be done here.

Judy Woodruff:

So, now let’s turn the corner and talk about this antibody testing.

Now, this is something different from the testing as to whether you actively have COVID-19 right now, where we think about the swab. This is different, isn’t it?

Miles O’Brien:


It’s kind of a question of tense. If you want to know if somebody in the moment has the coronavirus present in their system, the way you do that is a genetic test. Look for the genetic fingerprint of the virus itself.

But if you want to find out if somebody had it in the past, the way to do that is to go with an antibody test.

Antibodies are the foot soldiers of our immune system. They are proteins created by white blood cells that are specifically tailored to identify and help attack invaders. Most of us have all kinds of antibodies in our system to help ward off a whole host of infections.

Of course, the problem with this novel coronavirus is, it gets free rein, no antibodies to stop it. But when our immune system figures out what the threat looks like, our white blood cells get busy, producing new anti-virus foot soldiers, antibodies to the rescue.

They are tailor-made, like puzzle pieces, to attach to the new invader, and hopefully protect from it. In essence, a test puts a piece of the virus in contact with some blood. If the blood contains the antibodies designed to fight the novel coronavirus, they will be activated, causing a detectable chemical reaction.

Judy Woodruff:

And, Miles, how do they know they’re testing for the right antibody? This is a newly discovered virus. We’re hearing a lot about a high rate of inaccuracy.

Miles O’Brien:

Yes, it’s complicated science, to say the least. And it’s on an urgent deadline.

Having a test that can pick out the right type of antibody in the sea of other antibodies is the key. Scientists at the University of California, San Francisco, and U.C. Berkeley have started testing all these antibody tests which are appearing on the market like mushrooms.

None of a dozen tests — I repeat this — none of the tests that they have looked at and evaluated make the grade. There are all kinds of false positives and false negatives.

Judy Woodruff:

And, Miles, that is so discouraging to hear, because we know, in order to make a lot of progress toward ending this shutdown, stay-at-home, social distancing, we’re going to have to know a lot more about who’s been exposed and who isn’t contagious anymore.

Miles O’Brien:


I mean, the one good thing about these tests, once we find accurate ones, is, it helps us understand how widespread the virus is. That’s one thing. But we all want to get back to work. And we all want to know who’s got immunity and who’s safe to go back to work.

But that’s a much bigger challenge, because scientists can’t say even that, if they find those antibodies that are telltale, if those particular antibodies are protective. So it even gets more complicated.

So, there’s no way to determine right now if anyone has any immunity to SARS-CoV-2.

We spoke with immunologist Alex Marson, who is at UCSF and part of the U.C. Berkeley team as well.

Alex Marson:

Having a test that will tell us easily who’s protected from reinfection, it’s all of our hopes. There’s a lot of work ahead to be done.

But I — one message I want to get out there very, very clearly, none of these tests should currently give anyone a feeling that they’re safe from reinfection and modify their behavior to take on more risk. We’re just not there yet.

Miles O’Brien:

So, those are really important words from the scientists. We hope everybody takes those to heart.

Scientists say the experience we have had historically with other coronaviruses — and, after all, the common cold is a coronavirus — indicate that we should get immunity. That’s just the way it generally goes.

But, as you pointed out, this is all new turf. And so none of that is proven. It’s hopeful that it will happen. There’s no one that thinks it will be different this time. But science still has to bear this out, Judy.

Judy Woodruff:

So much work being done, and so much work yet to be done.

Miles O’Brien bringing us up to date.

Miles, we thank you.

Miles O’Brien:

You’re welcome, Judy.

Banner image credit: Mitch Butler/PBS NewsHour.

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