NOVA producer Caitlin Saks got the unusual opportunity to investigate her own blood to find out what exactly antibodies are, why public health professionals are eager to roll out antibody testing, and just what these tests can—and can’t—tell us.
Why Antibody Tests Don’t Yet Reveal Coronavirus Immunity
Published: July 16, 2020
Caitlin Saks: Could this blood test tell if you're immune to COVID-19? In recent weeks, it seems like everybody's been talking about...
Pundit: Those antibodies.
Pundit: Antibody tests.
Saks: Antibody tests have taken center stage as the crucial new tool for understanding how widespread the pandemic is. And recently,
Duane Wesemann: Do you get your blood drawn a lot?
Saks: No. I was lucky enough to be tested to see if I have these highly sought after antibodies.
Wesemann: Then we're going to do some analysis on the antibodies.
Saks: But what are these antibodies? And what do the results really mean?
Galit Alter: So I do call antibodies magic bullets. I might not be the only person in the world that calls them magic bullets.
Saks: Galit Alter is an antibody aficionado. In normal times, she studies how these magic molecules work.
Alter: Essentially what antibodies are, are the immune system's ability to make molecules that go around the entire body, survey all the different tissues, and then as soon as antibodies see a pathogen, they will stick on to that surface, and they will mark that surface. The entire immune system knows that there is something going on with that particular cell, and that pathogen must be destroyed.
Saks: And here's the neat thing about antibodies. After they evolve in your body to take out specific pathogens, they then stick around in your blood for a while, leaving an archive of what you've been exposed to and therefore what you might be immune to.
Alter: My laboratory has been focusing on the development of tools that can tell us how much antibody to Coronavirus we have in our blood. By look for antibodies, you could tell if somebody had seen that virus, even if they were no longer shedding that virus.
Saks: In Boston, Galit is working with Duane Wesemann to study hundreds of blood samples to see who has antibodies and if they make people immune to COVID-19.
Alter: Thanks for bringing them over.
Saks: Duane actually delivered samples to Galit while we were filming with her.
Alter: Okay, that's a good batch.
Saks: That's how I lucked into getting an antibody test. Hey there.
Wesemann: Hey, how's it going?
Saks: I'm ready.
Wesemann: So your blood sample was initially received by our laboratory, and then we ran your plasma samples against the virus, and we asked which antibodies are binding to the virus. And so when we checked your sample, we found that there was no binding to any of these. I see that you are a bit disappointed by this.
Saks: I had felt a little sick back in March, and the thinking was well, if I had been exposed then maybe I already got it, I'm already immune.
Wesemann: I should say, too, that even though we want to have antibodies to this virus, it's not clear the degree to which having antibodies to the virus will protect us from an infection.
Alter: It is not that just by having a positive antibody test that you are automatically ready to reenter the population. The last thing we want to do is to tell somebody that they have antibodies, have them reenter the workplace, have them re-exposed, and for reasons that we cannot completely understand, develop a much more severe disease.
Saks: So, if these antibody tests can't tell if someone is immune, what are they good for?
Alter: We don't understand how many people in the general population have truly been exposed or infected, even without their own knowledge. What we really need is these tools that will give us a much better understanding of who had been exposed and who was infected.
Saks: My test was just part of a larger study. The only thing it tells me personally is that I was not exposed. But getting this sort of information on a larger scale will tell us how widespread the virus is and we'll also start to understand what that precious immunity actually looks like. For that, lots of people need to be tested and tracked to understand which antibodies and at which levels confer immunity and for how long.
Alter: So let's say hypothetically speaking, we could get a group of 100 individuals that all had antibodies to this novel Coronavirus. And let's say that we could group them into those that had high levels or medium levels or low levels. And let's say we could study them over a given period of time. We could look at the number of infections that reoccur in individuals in these different antibody categories and what are the characteristics of an antibody that makes somebody immune to the infection. This type of analysis allows us to do now, for the first time, is to define the absolute threshold or the level of antibody that gives you complete protection from disease.
Saks: That is, if antibodies to COVID-19 do, indeed, make us immune at all, which most experts agree is likely but not certain. So when will we have these immunity tests? When will I be able to go to the grocery store and know that I can touch everything on the shelves?
Wesemann: Right. I know that's your dream, to go to the grocery store and touch everything because whenever you can't do it, that's just the thing you want to do now, right? It will take some time to make sure we understand the quality of the antibody tests and to understand what it really means to have antibodies to the virus. Until we understand what really it means to have antibodies, it's good to play it safe.
Saks: I get it. Hearing we don't know yet is not a very satisfying conclusion. I wish my blood test could've told me I'm safe. We all wanna get back to normal, but before we can do that, we need to learn a lot more about this virus. And scientists all around the world are racing to do just that. So for now, most public health experts say staying home is the best way to keep yourself and those who can't stay home safe. And if you wanna learn more about what scientists are discovering, check out NOVA's "Decoding COVID-19."
Producer/Reporter: Caitlin Saks
Digital Producer/Editor: Arlo Perez
Camera: Stephen McCarthy
Sound: Steve Bores
Research and Production Assistance: Sukee Bennett, Angelica Coleman,
Ari Daniel, Robin Kazmier, Christina Monnen
Additional Footage and Visuals: Pixar, Disney Studios
© 2020 WGBH Educational Foundation