Short Wave - Why Herd Immunity Won't Save Us

Episode Date: August 10, 2020

Herd immunity. It's the idea that enough people become immune to an infectious disease that it's no longer likely to spread. It makes sense theoretically. But as NPR's Geoff Brumfiel tells us, the reality — in this coronavirus pandemic and without a vaccine — is potentially full of risk and maybe even unachievable.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. This pandemic has upended our world. It's cost millions of people their jobs, closed schools, taken a lot of lives. It's had such a huge effect in such a short period of time. So it's understandable that many people comfort themselves by thinking this will pass. Sooner or later, this virus will just go away. Like everyone wants a way out psychologically, right? Because no one's ever coped with something of the scale.

And it's not like a crisis like a hurricane or 9-11 where it's like time bound or geographically bound. This is like everyone everywhere for indefinitely right now appeals to people, right? That's Debbie Schreeder, a global health expert at the University of Edinburgh Medical School. And there is a theoretical way this could end. If enough people catch coronavirus and then become immune, the virus doesn't have to be. have anywhere to go and it starts to kind of burn itself out. Soon, even the people who haven't caught it are safe. This idea called natural herd immunity has really caught on in some circles. The rampant belief that we should relax and facilitate herd immunity.

Heard immunity. In theory, building immunity to help slow it even further. But as good as herd immunity might look on paper, the real world is turning out to be a lot more complicated. All over the globe, millions are being infected, but the coronavirus is still here. I think it's going to be with us probably forever at this point. I mean, at a global scale, it's going to be with us, and it's how we decide to live with it. So today on the show, herd immunity, what it is, why it became so popular in this pandemic, and why it probably just isn't going to happen. All right. Today, we are talking about. herd immunity with NPR science correspondent Jeff Brumfield. Hey, Jeff.

Hi, Maddie. So I heard about herd immunity as a young, insufferable biologist, but Jeff, you cover, like, physics and nukes and stuff like that. How did you hear about this? I learned about it from a guy in his backyard on a YouTube video I watched. Jeff, can you just... Okay, you know what? I'm just glad you're interested in it. Never mind. Go on. Look, hear me out. It was March, and COVID was raging in Italy, and it was really, really becoming clear that the U.S. and the U.K.

And places like that, we're going to have to take some drastic action. And in the U.K. in particular, the government was looking for ways to avoid a lockdown. You mean like a very strict lockdown with everything closed and movement restricted? Exactly, exactly. Actually, slightly counterintuitively, things like closing schools and stopping big gatherings don't work as well, perhaps as people think. Prime Minister Boris Johnson goes on national television and basically says, we're thinking of just sort of trying to ride this thing out.

One of the theories is that, you know, perhaps you could sort of take it on the chin in one go and allow the disease, as it were, to move through the population without really taking as many draconian measures. Now, the government really isn't saying what they mean by take it on the chin, But then on YouTube, this pediatrist named Robert Isaacs shows up in his garden with a couple of buckets of water. This bucket here represents the population. That bottle represents the health care system. And the hole in the bottom of the bottle there represents people getting better from the virus. This video got more than 3 million views, including me.

And here's how he explained it. The big bucket is all the uninfected people in Britain. You pour that through the health care system, and out the bottom come immune people. So broadly the idea is this. People are going to get sick. There's not a whole lot you can do about that. So all you can do is try and slow down the spread just enough so the hospitals aren't overwhelmed, so that health care bucket doesn't overflow.

If we have a slow, steady stream of cases, the healthcare system can cope with it. You tell older and other vulnerable groups of people to hide in their homes. And eventually, almost everyone in the UK will have had COVID. The disease can't spread anymore and the vulnerable groups can come out of hiding. The economy doesn't completely collapse and life goes on. Jeff, I am hashtag screaming inside my heart at you right now because what you're describing is not actually how herd immunity works in big populations. I think in pretty much every situation, like, measles or polio, we've reached herd immunity with the help from vaccines, not naturally or whatever this is called.

Okay, so yeah, natural herd immunity is not the norm. Tell me how real herd immunity works. Well, okay, so basically large-scale vaccination creates a population where so many people are immune to, let's say, a virus, that the virus can't really get a foothold in that population, if that makes sense. So even if a few people aren't vaccinated, they're still protecting. because the virus isn't just there, thus herd immunity, a few protected by the greater herd. But, you know, letting tens of millions of people get sick with COVID when you don't have that essential immune population is not the same thing, Jeff.

Yeah. So I know that now because I got off YouTube and I called scientists like Josh Schiffer. I guess first of all, the idea of trying to get to herd immunity without a vaccine as a strategy is just a terrible idea. Shiffers an infectious disease clinician at the Fred Hutchinson Cancer Research Center in Seattle. His group does mathematical modeling on COVID, and he says that letting the virus burn through the population, as you just mentioned, would make a lot of people sick and it would cause a lot of people to die. It's very difficult to project the number of deaths, but I think we're certainly talking north of a million, probably much more. Yeah, I mean, this idea is like pretty much just out of the question.

Right. And I mean, look, as soon as governments start floating these ideas of letting the virus pass through the population, scientists start projecting astronomical death counts that would result. And so herd immunity is an official policy basically dies before it ever gets started. There is just no way politically to embrace the strategy. The UK goes into lockdown, as does pretty much everywhere else on Earth. But the idea of natural herd immunity doesn't really die. And this is why I find interesting. There's still this sort of idea that somehow the virus will eventually just vanish. And you've been hearing this a lot in recent weeks, in particular from one individual, our president, President Trump.

This thing's going away. It will go away like things go away. Yeah, I mean, Trump's track record on science in this pandemic has been atrocious, Jeff. Let's be real. But I feel like he's not alone. There are absolutely people out there with a sort of vague hope that COVID will just pass. And I'm here to tell you, after an awful lot of reporting on this, that most researchers think that's not how this is going to end. Herd immunity just isn't going to work. And actually, we've already been seeing things happening in the world that make that even more clear. So let's talk about that. Where should we start? I think a really good place to start is by talking about Sweden. It's an interesting test case. Sweden never officially pursued a herd immunity

approach, but they got kind of as close as any country has. They had this really light lockdown. They limited gatherings to 50 people or less, kept everything open with minor restrictions like table-only seating at restaurants. And in the spring, Swedish officials were bragging that Stockholm might effectively reach herd immunity by the end of May. But it hasn't happened. Blood tests showed not that many people in Sweden have been infected with the coronavirus. It's maybe 5%. And for natural herd immunity for this virus, the number has to reach more like 50 to 80%. Meanwhile, Sweden has had higher death rates than its Nordic neighbors like Norway, and their economy is suffering badly. So this has not worked well in practice. So what happened there, Jeff? I'm actually curious why more people

didn't get sick if they were essentially doing not much to combat it. We don't really have a clear answer to that yet. But Devi Schreeder, who you heard at the top, she has what I think is a really credible theory about what's going on. People have just changed their behavior because they don't want to get the virus. And nobody wants to be part of the hurt. Let's just say it that way. So basically people saw what was going on and decided like, I'm not going to do that. I'm going to stay home. You know, maybe it wasn't as coordinated and resulted in more deaths, but it still kept overall infections pretty low. Right. Exactly. And that really brings us to reason number two why herd immunity isn't going to work because it is possible to slow down the

coronavirus. And if you do do it in a coordinated way, as some nations have, it's basically possible to effectively stop its spread. So the example I like to think about is South Korea. That's Jeffrey Schaman. He's a researcher at Columbia University who's looked closely at this. They're getting 50 cases a day right now. If they were to hold on for another thousand days, which is almost three years, they'd have 50,000 cases, which is 0.1%. of their population. It would literally take hundreds and hundreds of years to reach herd immunity levels at that rate. Right. I mean, a lot of people have been infected by the coronavirus, but astronomically more people have not. I mean, even New York City, arguably the worst

outbreak in the United States, we weren't getting anywhere near 50 to 80 percent of that population infected. Exactly. This also sort of brings up the last problem with natural herd immunity, which is actually about individual immunity. Schaman studied four coronaviruses that cause common colds, and he found they can make people sick twice. Some of them were four to eight weeks separated from the previous infection, which is rapid, and that might have been a relapse. But others we clearly know are different.

They were eight to 11 months apart. And this is something we've talked about on the show before. We still don't know whether reinfection is possible. But what we do know is that immunity to COVID-19 is, really complicated. It might be that a person could get reinfected after a few years or that you could be partially protected, that kind of stuff. Right. But natural herd immunity can't work if there's anything short of full permanent immunity. If somebody can get COVID twice, even if that second infection is mild for them, they can spread it and then the herd isn't protected. Yeah. And if that's the

case, then COVID will become what's called endemic. A lot of people think this is what's going to happen. And basically it means it will continue circulating in the population indefinitely. It won't be as bad as the first waves, but people will keep catching it, keep getting sick, and some of them will keep dying. You know, the flu is a good example of a virus that's endemic in the United States. Exactly. And look, that's a real problem because vulnerable populations will be at risk forever. And we now know that even people who survive COVID can suffer long-term health consequences.

And the disease is hitting poor people and marginalized groups around the world harder than others. So basically the more people that get infected, the bigger the burden on our health systems, the more inequity will grow. Basically, everything gets worse. Come on, Jeff. I mean, I have to say nothing you've said today really surprised me. But just talking about another thing, even though it's a terrible idea, that won't work, is kind of a bummer. It is a bummer. But, you know, once you let go of your magical.

thinking and let go of this idea that somehow this will all just disappear after that depression comes acceptance. And once you accept that COVID isn't going away on its own, then you realize we've got to fight it and we can fight this, Maddie. Ooh, pep talk, Jeff, go on. Wear a mask, wash your hands. How many times do we say that on shortwave? It's like every single day, basically, but it matters. At a societal level, we can test, we can contact trace, we can isolate the sick. Now, none of this is going to completely eliminate the coronavirus, but things can get a whole lot better than they are right now. You, me, shortwave listeners, we can literally save lives doing this stuff. Yeah. And I mean, science will help too, right?

We're going to get better at testing. We'll get better at treatment. And vaccines, even if they don't create herd immunity, they could really change the game for us. You know, where I've finally come down on this, Maddie, is that we are highly intelligent primates with the sweet posable thumbs. And coronavirus is a sack of RNA with a bad haircut. Honestly, the mix of trash talk inspirational Jeff is my favorite Jeff. Oh, that sounds like a compliment to me. It's true.

I appreciate you right now, Jeff. But one thing, never bring a random YouTube video explanation on this show again, young man. I promise. This episode was produced by Abby Wendell, edited by Viet Le and fact-checked by Burley-McCoy. I'm Maddie Safia, and this is Shortwave. from NPR.