Today, Explained - A vaccine for malaria

Episode Date: October 7, 2021

But also, should we kill all the mosquitoes? Today’s show was produced by Will Reid with help from Miles Bryan, edited by Matt Collette, engineered by Efim Shapiro, fact-checked by Laura Bullard and hosted by Sean Rameswaram. Victoria Chamberlin was the mosquito. Transcript at vox.com/todayexplained Support Today, Explained by making a financial contribution to Vox! bit.ly/givepodcasts Learn more about your ad choices. Visit podcastchoices.com/adchoices

Get groceries delivered across the GTA from Real Canadian Superstore with PC Express. Shop online for super prices and super savings. Try it today and get up to $75 in PC Optimum Points. Visit superstore.ca to get started. What do you think the deadliest animal on Earth is? I'll give you a hint. You hate them. They're tiny.

You've murdered many of them. Yes, it's the motherf***ing mosquito. Sure, you've probably never died from a mosquito bite, but millions upon millions have because malaria. So malaria is a huge problem in poor parts of the world. It kills more than 400,000 people a year. Kelsey Piper, Vox's future perfect section. So scientists have been working really hard to develop a vaccine and they're finally getting somewhere. Dear colleagues and friends. The World Health Organization announced on Wednesday that there is now a vaccine that they recommend to children in high-risk areas that will reduce their odds

of dying of malaria. Using this vaccine in addition to existing tools to prevent malaria could save tens of thousands of young lives each year. I started my career as a malaria researcher and I longed for the day that we would have an effective vaccine against this ancient and terrible disease. And today is that day. Hmm. Does it have a fun name, like Spike Facts? Spike Facts! Yeah, it's called Mescherix. Mescherix.

Mescherix, for when you can't kill mosquitoes like me. It used to be in trials it was called RTS,S. That's not as good. Yeah, no, Meskerix is a huge step up in branding, and the vaccine is a huge step up in the fight against malaria. Meskerix, because we can't just kill all the mosquitoes. That would be ridiculous. malaria. Malaria kills 400,000 people a year, and that's mostly young children and pregnant women. It tends not to affect adults and people with a healthy immune system. And of course,

adults in high malaria areas have usually fought it off repeatedly and have some immunity, but it hits young kids really hard. Remind the good people how malaria makes you sick. So the parasite that causes the malaria disease is carried by mosquitoes. Here is the female Anopheles mosquito feeding, with her body held high in a straight line with her long beak. It infects the mosquitoes. When the mosquitoes bite us, it infects us. She sticks her beak through the skin, secreting saliva to make the beak go in easier. With the saliva, malaria germs are carried into the blood.

And it completes its life cycle by reproducing in the liver, entering the blood, and then being passed along to the next mosquito to bite you. Recurring cycles of chills and fever sap the victim's strength. Along the way, it can cause intense fevers and kill young people whose immune system can't fight it off. Why has it taken so long to reach this point where we might have a, you know, efficacious vaccine? So vaccines for viruses like COVID or like smallpox or like polio are just easier to develop than a vaccine against a parasite. A virus is very small. It's pretty compact.

It has very few parts and it needs all of them. A parasite is an entire living organism. And so figuring out what part of it you want to counter, what part of it your antibodies need to recognize is harder. And then making matters worse, malaria is not a disease where you get it once and you're immune for life. Like smallpox, you caught it once, you never get sick again. Malaria, you can get malaria up to like six times a year. And in fact, even among people who don't die of malaria, it can have huge long-term consequences just because constantly fighting off the serious illness leaves your body weaker, means you don't have the chance to grow up as healthy and, you know, develop as a fully healthy person. So beating that is a huge deal. And it's taken scientists sort of a long time to narrow down what part of the parasite life cycle

we can most effectively target, what proteins we're going for, what antibodies we even want to teach the body to make. But they're getting somewhere. How long have they been at it? There have been efforts to develop a malaria vaccine that go back a century. Mosquerix actually, work on it started in the 1980s. That's when GlaxoSmithKline, which is the pharma company that developed this, first put together the pieces that became RTSS. Okay, so a really long time. Yeah, it's an obvious one to go for as soon as you have the concept that we can use vaccines to control infectious disease. Malaria is really bad. It's one of the worst ones out there. And a vaccine is going to be a huge part of any strategy to

control it. Currently, we do preventative prophylactic distribution of medications against malaria. We do embed nets. Those help a lot, but they can only get you so far. Whereas a vaccine, if you can make it universal enough, if the vaccine is effective enough, can really just change the game. What did scientists figure out here with RTS,S, aka Mesquerics? So in early stages of figuring out how to fight malaria, there were efforts to target it at different points in the parasite's life. Like, do you want to target it as soon as it gets injected into the body? Do you want to hit it in the liver where it's multiplying? A lot of those turned out to be dead ends. RTSS and, you know, other efforts at a successful malaria vaccine, try and hit it early, prevent it from getting to the liver and reproducing in the first place. And then that can stop you from getting as sick.

And they've also gotten a better understanding of how to prompt the body to do that, like which specific things you need to teach the body to look out for so that it can mount a strong immune response when the parasite shows up. So how effective is this Meskerix business? So unfortunately, not as effective as we'd like. It depends a little bit on how you measure it. But in general, for someone who's gotten the whole course of shots, you see like a 30% reduction in the risk of severe disease from malaria. Now, when 400,000 people are dying every year, 30% reduction, that's still very real. But it's not the sort of dream vaccine that, you know, would just mean malaria was a thing of the past. And now that vaccines are so top of mind for a lot of people, I mean, how does this one get delivered? Is it one shot? Is it two? Is it four? How does it work? It's four shots, three of them a month apart, and then a booster a year later.

That's obviously a lot to administer. But since malaria is so hard to teach the body to make an immune response against, it's kind of what you got to do. Does that mean that this vaccine is presenting an additional challenge of getting someone to come back twice and then even a third time for a booster shot? So obviously, that's a huge challenge in vaccine administration. But what the World Health Organization recommended Wednesday is that nations make this part of their normal childhood immunization program. So this is something that like the measles vaccine, like

the diphtheria or whatever else, you're administering to young kids as part of routine medical care. So a lot of the time that means you're traveling around in these communities frequently anyway in order to get those kids all their other shots, which hopefully makes it a little easier to add the malaria shot into the mix, you know, without having too many problems with uptake. And they've had pretty solid uptake in the countries, Ghana and Kenya and Malawi, where they did a pilot program. So, you know, despite the four shots, they're really able to get people to get the care that their kids need. Okay. And this four-shot vaccine for malaria, Meskerix, it's the first one the WHO has ever recommended. Will it be the last?

Hopefully not. So 30% efficacy, it's much better than nothing. It's not really good enough to turn around the whole fight against malaria. And there are vaccines in the works that look like they're a little bit better. One study came out in April. It was a phase two clinical trial. So in a real population, but pretty small scale that found something like a 77% reduction in severe malaria cases. That's a lot more. It's huge. It's really exciting. And that one is now in phase three trials, which are larger scale and will be more definitive. And if that holds up, then we might only have muscaria, you know, for a few years before we're able to replace it with something even better. And I know of things that are earlier in the pipeline and, you know, obviously have a high chance of not panning out, but that have the potential to be even better. So I do think eventually we have a shot at getting one of these vaccines that is as effective against malaria as vaccines against measles, which is

like 95% effective or COVID, which is, yeah, in like 90% effective against the original variant. And what happens then? Do we get rid of malaria? Well, that would be the hope. Okay, Kelsey, we have to take a break because that's the nature of this show. But I have to ask, when we get back, can we talk about just killing all the mosquitoes? Would that help? Oh, man, I would love to kill all the mosquitoes. That full plan, probably not going to happen. But there are some things sort of like it in the works. Uh, guys?

Uh, I'm still here. I heard that. Support for Today Explained comes from Aura. Aura believes that sharing pictures is a great way to keep up with family, and Aura says it's never been easier thanks to their digital picture frames. They were named the number one digital photo frame by Wirecutter. Aura frames make it easy to share unlimited photos and videos directly from your phone to the frame. When you give an Aura frame as a gift,

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Please play responsibly. If you have any questions or concerns about your gambling or someone close to you, please contact Connex Ontario at 1-866-531-2600 to speak to an advisor free of charge. BetMGM operates pursuant to an operating agreement with iGaming Ontario. Kelsey, not all mosquitoes are malarial, obviously, yes? Yeah, that's right. In fact, the overwhelming majority of species of mosquito don't bite humans at all.

And of the ones that bite humans, there's really only a couple, and really only one major one that carries the malarial parasite. And where do we find this one exceptionally nasty mosquito? So the mosquitoes that can carry malaria are the ones of the genus Anopheles. This is the story of an outcast. You all know her name, Anopheles amy is the story of an outcast. You all know her name, Anopheles Annie, the malaria mosquito. And those live all over the world. It's just that in most of the world, they don't give you malaria. If malaria were introduced, there would be Anopheles mosquitoes,

you know, in the U.S., in Europe, everywhere but Antarctica, that could carry it. But we've successfully wiped out the malaria parasite. To look at me now, you wouldn't hardly believe it. But back in the good old days, I was really some stuff. So this isn't really a question of getting rid of all of the mosquitoes. It's about getting rid of these kinds of mosquitoes that have malaria. Yes. So obviously, if no mosquitoes ever bit anybody

again, I think we would all love that. But in terms of minimizing the impact on the ecology and not having a risk of serious environmental side effects, most proposals to use gene drives or use sterile male mosquitoes to wipe out malarial mosquitoes have focused very narrowly on the specific kinds of mosquitoes that bite humans and can carry malaria. So we might still have other mosquitoes around. And, you know, the mosquitoes that only bite livestock, probably we don't care as much about those being around. And that way we just don't have to worry about, you know, majorly disrupting ecosystems by taking out an entire kind of animal, even if it's a kind of animal who we all hate. You're answering a question I have for you here in advance of me asking it,

which is, would it be bad to just get rid of all of the mosquitoes? We don't know. I think it might be fine. But since we don't know, and since it's a little bit hard to reverse, probably it's smarter to do something more conservative, like get rid of all the malaria-carrying or human-biting mosquitoes. The Florida Keys Mosquito District has started releasing about 12,000 genetically modified non-biting mosquitoes. The Florida Keys Mosquito District has started releasing about 12,000 genetically modified non-biting mosquitoes, part of a pilot project the EPA approved last May.

You know, which is narrower and almost definitely safe. The plan? Test to see if a genetically modified mosquito is a better alternative to spraying insecticides to control the type of mosquito carrying deadly viruses in the Keys, including Zika, dengue, and yellow fevers. I think we've talked about some of the strategies here on the show before, at least one maybe where Bill Gates wants to edit the genes of these malarial mosquitoes using CRISPR. Correct me if I'm getting anything wrong, but...

Yeah, no, that is a proposal that's been put forward. And so we're working on genes that either reduce mosquito populations or eliminate the anophelium mosquitoes. What else is out there? All right, so one option, yeah, is putting a sort of genetic time bomb in some mosquitoes where maybe they can have children, but those children will be sterile. And you put those mosquitoes out there and then you have a next generation of mosquitoes that all have this gene for sterility or many of them carry it on. And then if you design your gene drive correctly, after a couple of generations, you've wiped the species out. There's obviously a lot of challenges in implementing this,

but researchers have plans for it. And given that 400,000 people a year are dying, doing testing and figuring out how that works is definitely a priority and something I think we should honestly be investing more in. Another option, which is a little bit less scary to audiences, it doesn't have the phrase gene drive in it, is you flood an area with tons of sterile male mosquitoes. And then the female mosquitoes will mate with your sterile male mosquitoes instead of with the regular male mosquitoes. Okay. And then they just don't have offspring because you flooded the area with sterile males.

Oh, no. And since the sterile males will die off, this is a temporary intervention. So we can sort of do it, wipe out the mosquitoes basically to a tiny fraction of their original population for one mosquito generation. They'll come back over time, but that lets us test, like, okay, we wiped these mosquitoes out. Did that have any negative ecological consequences? Did it have the desired effects on malaria? We can sort of do things like that, and there have been some pilots of projects like this, and see, okay, wiping out mosquitoes seems to be going pretty well. So all these strategies are based around tricky sex?

That's honestly, many of the strategies I've heard of basically amount to that. Oh yeah. You want to mess in some way with the mosquito life cycle. And in general, the easiest way to do that is either interfering with reproduction or interfering down the line with subsequent generations' reproduction. Do we have any idea at the end of the day what the likelihood is that in order to eradicate malaria that we'll need both of these strategies, a efficacious vaccine and maybe some sort of tricky sex mosquito situation? So I think when something is killing 400,000 people a year, you proceed on all

fronts, right? You try and design a great vaccine. You try and design a great eradication plan. In principle, maybe the eradication plan would work without vaccines, but maybe we come up with something that partially works but doesn't fully solve this for us, and then the vaccines make a huge difference too. Or maybe we end up doing so well with vaccination that we feel a little less urgency on rolling out a gene drive eradication type solution. It just gives us a little bit more opportunity to save lives and figure out the exact right way to do eradication. I think just when the stakes are this high, it's worth sort of doing everything we can. And in the meantime, is it still cool if we just murder as many mosquitoes as we can? I see no scientific reason why you shouldn't hate mosquitoes.

They're the worst. They kill tons of children. You know, a grudge against mosquitoes is one of the most justified grudges you could possibly have. Blessings. Thank you so much, Kelsey. Kelsey Piper is a very evil staff writer for Future Perfect at Thought. Will Reed and Miles Bryan produce this episode? They seem okay. And Sean Ramos-Marm is the host. It's Today Explained. you