Immunity to Coronavirus: Why It's so Complicated

in your body. It's not just anybodies that are fighting the virus. B cells and T cells also helped fight illnesses after anybody's have disappeared. Katherine Wu, science reporter at Smithsonian Magazine, joins us for why immunity that the coronavirus is so complicated. Thanks for joining us, Katherine, Thank you for inviting me. It's great to be here. I wanted

to talk about the coronavirus COVID nineteen. We've been battling this for some months now, and one of the things that we haven't had a chance to really wrap our head around is immunity from the virus. Once you get it, Are you even completely immune from it? And there's a lot of stuff that goes into it. It's pretty complicated in the way it works in our bodies. So Catherine helped us out a little bit to understand why immunity

to this has been so complicated so far. Yeah, I mean, I'm really glad that you're looking into this, because it's best a complicated question, and I think during such a chaotic time when there are lives at stakes, people really want clear cut answers, and I as the report that

we don't have a lot of those right now. I think the most important takeaway at this point is that even though we have tests and a lot of people working very hard on this disease and how to fight it, we don't really have clear cut answers on whether or not people are going to be protected from getting infective with the virus a second time, even if they've recovered

from about a public night scene. The way that I sort of look at this is a lot of people by now have heard of antibody tests, either of the tests that searching your blood for those immune molecules that your body makes in response to a pathogen that's trying to infect you kind of like dusting for fingerprints after a crime has occurred at a crime scene. It's evidence that something has been in your body. But that's a very past focused book at the disease. It doesn't tell

you a whole lot about the speaker. Yeah, And one of the things, whether anybody's, that I didn't really know about too much, is that they have a kind of a short lifespan, and they disappear from your blood after a few weeks or months, depending on how strong your immune system response was. And it's really these other cells in your body that kind of remember what those antibodies were.

So if the same pathogen comes back into your body obviously we're talking about COVID nineteen, if you get infected again or something, these other cells are the ones that remanufacture those antibodies. So there's a lot of other stuff involved in really making your body continue to fight these diseases. Yeah, exactly, that's a really pretty point, So I thinks drive home

so specifically about the antibodies, You're exactly right. Those are molecules made by the body by a population called B cells, And it's sort of the difference between you know that old addage like you know, give them person a fish and they eat for a day, keeps them how to fish and they can eat for life. Those antibodies are pretty temporary, but what is really important are those B cells, which remember how to make those antibodies against the virus itself.

And so what you really want is those B cells to stick out around some then will kind of go dormant after you've recovered from an infesttion and then their ideal circumstances so hang around in your body. So then we'll keep dividing or just hang out for a really

long time in the bone marrow. And then if that pathogen kind of comes to invade your body again, they will recognize that the pathogen hast come back and manifest those antibodies for a second time, and the response will be even stronger and faster than before, possibly so fast and so strong that you may not even experience symptoms the second time. Yeah, And of course that's what everybody

would hope for that they can have. So there's also there's B cells, and then there's T cells T as in TOM, and some of these cells also help in this same thing, manufacturing and helping fight the viruses once they come back. So B cells and T cells are kind of two prongs of what's called the adaptive I mean response, and that's the kind of slow wave that kicks in roughly a week into infection, depending on what

pathogen we're really talking about. And T cells serve kind of a different function, Like I guess I see B cells as weapons factories they're making antibodies, whereas T cells can actually accomplish a lot on their own. T cells can either help B cells make antibodies, so they're sort of supporting the antibody factories as they're churning these really important disease fighting molecules out, or T cells can sort

of fight their own war. They can actually identify your own cells like the rest of the cells in your body, like the cells that might line your airway, recognize the ones that have been infested with a virus, and actually send the signals to tell them to self destruct, because at that point they figure that sells the lost cause it's been effect of the pathogen. The best way to deal with the situation is to make that cell get rid of itself, and that will also theoretically destroy the

viruses inside of it. Do we have any information yet I know we're very uncertain on this whole thing. I had been reading about study in South Korea that basically said some people that have retested positive again for coronavirus weren't shedding active particles of the virus. In other words, they were clearing all those people. If you had COVID nineteen and you recovered, you were no longer infectious to other people. So it kind of plays into this whole thing.

But has there been any other studies going around. That's the only one that I've seen. Really, I'm glad you brought up that bit of news because I think they have a little bit of nuance there that's may be important to get into. I feel like there were a few reports coming out in early days talking about reinfection, like people were testing positive, having symptoms, then recovering and testing negative. And in this case, I'm talking about the

test that looks for the virus, not antibody. So this is a diagnostic test that can tell whether or not the viruses in your body, and probably active people were testing positive, than negative, then positive again, and people were wondering are people getting reinfected? Does that mean that these people aren't And the into the virus, and we're just doomed to get infected over and over again. I think a lot of experts have since come forward to say

that these people probably we're fighting the virus. The virus sort of declined to very low, difficult to detect levels in their body, and the tests were missing the virus because it was so scarce in the body. And then after some time, maybe the immune system kind of relaxed and the virus maybe took the opportunity to sort of surge back to higher levels levels that were maybe triggering another bout of symptoms or making the virus detectable by

these tests again. And so I think in that sense, it's really difficult to say exactly what was going on inside the body. But you know, that doesn't necessarily bad news. There are a lot of pathogens, including viruses, bacteria, parasites that can kind of linger in the body. But if we're able to detect this early, this won't necessarily be universal for everyone, and we can develop treatments that can either keep the virus at extremely low levels so that

people aren't experiencing symptoms or are shedding the virus. That's kind of what happens with HIV and people can you know, live very long, healthy lives in that case, or you know, this will kind of inform when can we sort of target and treat the virus so that it doesn't establish maybe a population in the body that's going to be

this long lasting. But I definitely don't want to give people the impression that this is the norm or that they're going to be stuck with this virus permanently, just that that could be the case for a subpopulation of people. There's still so much yet to be learned about the virus and how it lives within the body and all, and it's important for vaccine development and all that, so hopefully soon we can start understanding a little bit more.

Catherine Wu, science reporter at Smithsonian Magazine, thank you very much for joining us. Thank you my Oscar Emiraz, and this has been your daily coronavirus update. Don't forget that. For today's big news stories, you can check me out on the Daily Dive podcast every Monday through Friday, So follow us on I Heart Radio or wherever you get your podcast.