This is a transcript of our episode “A super special shot: All about coronavirus vaccines”

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Gus: You’re listening to Brains On, where we’re serious about being curious.

Molly: Hey, Bob is still an okay time to video chat? It's been so long since I've seen you.

Bob: Yes, of course. I'm just working on my vaccine scrapbook. Let me pick it up and show you.

Molly: That's beautiful, Bob.

Bob: Thank you. I've made pages for every vaccine I've ever received. You know, each one has a different theme. You see, polka dots for the flu vaccine, zebra prints for tetanus and you can see I've used a lot of glitter for the measles, mumps, rubella. Sounds like the name of a disco tune, don't you think? Measles, mumps, rubella, measles, mumps, rubella. Well, anywhoodle. I'm decorating my COVID vaccine page in anticipation.

Molly: What theme did you choose?

Bob: Well, I can't decide. So I've made a few different options. Here's one with a burlap background, which provides some nice texture, I think, but look at this one. I hand embroidered some vines around the edge on this one, sort of garden themed. This one might be my favorite, I think. I decorated the page with my thumb prints, and then doodled on them to make them look like little bunnies. I haven't even started working on fonts yet.

Molly: You seem pretty busy. I better let you go.

Bob: Sure, Molly. Now, where's my glue stick? Darn it.


Molly: You're listening to Brains On for American Public Media. I'm Molly Bloom, and I am so happy to welcome back our co-host, Gus from Seattle. Hi, Gus.

Gus: Hi, Molly.

Molly: Gus has been the co-host for all of our Coronavirus episodes so far. This makes number seven. Gus, I just want to know, how is life going for you right now, overall?

Gus: It's been pretty good. It's not as boring as it was before. I've been doing a few new things.

Molly: What are you up to?

Gus: Let's see, I've been doing more rain walks because it rains a lot, lot, lot, lot, lot more in the winter here in Seattle. I've also been building a wooden playhouse with my dad.

Molly: That's cool. One you can go inside of?

Gus: Yes, it's in the side yard. It's just like a small wooden room with a slanted roof. We've already built the foundation and the floor.

Molly: Are you getting to use tools and stuff?

Gus: Yes, we've been using hammers and nails mostly, that's pretty much all we've been using, which is pretty typical, but that's all for now.

Molly: No saws yet?

Gus: No, no saws. I'm excited for the day that that happens.

Molly: Can you describe what a rain walk is?

Gus: It's what it sounds like. It's a walk in the rain and it's the best thing for the mind.

Molly: Well, since we last talked, there has been an exciting development.

Gus: People have started getting their COVID vaccines.

Molly: Yes. The first person was vaccinated against the Coronavirus here in the US in December and as of January 15th, over 10 million people have received a vaccine in the US. Gus, do you know anyone who's received the vaccine yet?

Gus: Yes, actually, let's see. There's my aunt Kim. She works at a dentist clinic, I'm pretty sure. She got the vaccine pretty early. There's also my older relatives who are getting it in like a couple of weeks or something. My grandma, my grandpa and two of my aunts, I think, they're going to get it soon.

Molly: That's really exciting. In the US, states are in charge of getting the vaccine to people. Depending on where you live, it might be a little different, but for most places, the first group of people to be vaccinated were nurses, doctors and other healthcare workers.

Gus: Then they started vaccinating people who live and work in nursing homes.

Molly: Now some states have started vaccinating people over 65 years old and other frontline workers like teachers. The fight against COVID-19 is far from over, but these vaccines are a big step forward towards getting it under control.

Gus: Today, we're going to answer this listener question.

Eyal: How do doctors make sure the vaccine is safe?

Molly: That is a great question, and that's Eyal, from Teaneck, New Jersey. You know what, Eyal? It really is amazing how quickly scientists have made these coronavirus vaccines.

Gus: Before, the quickest vaccine took four years to get ready, that was for the mumps.

Molly: But these first coronavirus vaccines took less than a year.

Gus: That's record-breaking speed.

Molly: It is, and one thing that really sped up these vaccines is that scientists have studied other coronaviruses before. The Coronavirus that causes COVID is not the only coronavirus. Other coronaviruses cause colds and some have caused other more serious diseases. You may have heard of them, they're called SARS and MERS.

Gus: Scientists have been studying these other coronaviruses for many years now.

Molly: By the time this new coronavirus popped up at the end of 2019, scientists had some ideas about how our bodies might get ready to fight a coronavirus like this one.

Gus: So scientists were ready to start working right away.

Molly: A lot of vaccines use a weakened virus or a dead virus to teach your body to recognize it.

Gus: But the two vaccines that have been approved in the US actually work a little differently. They don't contain any virus, instead, they use something called mRNA.

Molly: The M in mRNA stands for messenger. mRNA is a messenger molecule that tells your cells what to do. So the vaccine contains a teeny bit of this messenger code and this code says, make a tiny protein, and once the protein is made, this code gets destroyed, like a secret spy message or something. These mRNA vaccines tell your body to make a very specific protein, the protein that is on the coronavirus spikes. So your body makes this protein and your immune cells see it and they're like, "Whoa, what is this protein doing here? Tag and destroy." Then your immune cells create antibodies against this protein and destroy it. Now, if you get infected by an actual coronavirus, your body will recognize that tiny protein and say, "Hey, we remember you, get out of here."

Gus: If you weren't vaccinated, your body wouldn't be trained, so it wouldn't be ready to fight the coronavirus right away.

Molly: And in the time it takes your body to realize you're infected, you get sick.

Gus: That's why vaccines are awesome. They train our bodies to fight germs so that when we do meet them, we're ready to destroy them.

Molly: So that's how the mRNA vaccines work, but how do we know the vaccines are safe?

Gus: Any new medicines and vaccines go through a lot of tests to be sure they're safe for us.

Molly: First, scientists do lots of research in labs, once they're pretty sure a treatment will be safe and useful, people volunteer to try it out and report how it goes. Those tests in humans are called clinical trials. You can think of them almost like an obstacle course for a vaccine or medicine.

Announcer: Injections, pills, treatments, this is a clinical trial. We are testing you for safety, we are testing how much of you to give to people, then we are testing your safety again, and then once we're really, really sure you're safe, we are testing how well you work.

Whether you're a medicine or a vaccine, you already know a clinical trial will be your biggest test ever. Sure, you've strutted your stuff in cells and even animals before, you probably did really well in those experiments if you made it here, but a clinical trial is your first test in actual human people.

Vaccine: I can't wait to give these trials my best shot.

Announcer: Now, I want everyone to look around you. Do you see only medicines and vaccines?

Vaccine: No, he's an injection of saltwater.

Medicine: She's a pill made of baking soda and sugar.

Announcer: That's right. Treatments and vaccines aren't the only ones running through these clinical trials. In each trial, researchers will also test a version of the treatment that's meant to do nothing, it's called a placebo. Half the humans in a clinical trial will get treatment and the other half will get the placebo. No one will know who got what until the end. The test is how well you do compared to the placebo.

Vaccine: I don't need a do anything placebo to know I'm a good vaccine.

Announcer: Yes, you do. Scientists need to compare anything new, that's you, treatments, with something they already know about. Placebos are easy to know about. They don't do anything. Humans getting a placebo should see zero results. If a placebo does nothing as we'd expect, you can trust that trial, and more importantly, you can trust whatever that trial says about a treatment.

Here's how these clinical trials will go. Phase 1 is tests in about 100 humans. Scientists will see if they all stay healthy and decide how much treatment is the best amount. Then they'll do a Phase 2 test in a couple hundred people. Again, we're looking at if you are safe. After you prove you're safe in Phases 1 and 2, Phase 3 is a much bigger study in tens of thousands of people to study how well you work. Scientists will keep count of what happens in all of these tests and track those numbers closely. They call those numbers data. If researchers have any issues with your data or safety, they can stop a trial at any time. Now get out there and do your best.

Molly: In the clinical trials that tested vaccines against the coronavirus, half the people in each test got an actual vaccine.

Gus: The other half got an injection of saltwater, which would do nothing.

Molly: Then researchers just watched everyone in the trial closely. They waited and watched to see who got infected with the coronavirus and who didn't. Because the coronavirus has been spreading a lot this year, they actually collected a lot of data really fast. So far, two vaccines have been approved in the United States. Both of them work really well at stopping people from getting sick and preventing really bad cases of COVID-19.

Gus: There are more vaccines going through clinical trials right now.

Molly: At least two more are likely to be approved in the United States very soon. Okay, Gus, before we go any further, it's time for the mystery sound. Here it is.

(Mystery sound)

Molly: Do you have any guesses?

Gus: Maybe peeling off some protective plastic or maybe a lid or something?

Molly: I love that.

Gus: It sounds a little different. It's like a mix of peeling off a lid and ripping off a piece of paper.

Molly: Very good ears, Gus. We're going to hear it again and give you another chance to guess a little bit later in the show.


Molly: Scientists are still studying this coronavirus and the vaccines we now have against it. One question they're looking at is how long immunity lasts to this virus.

Gus: We talked to Apoorva Mandavilli. She's a science reporter for The New York Times.

Molly: We hopped on a zoom call with her recently.

Gus: If you do get COVID and then you get better, how long are you immune, if that happens?

Apoorva Mandavilli: Scientists have been looking at that and they've been tracking people who got better and seeing how long their immune response stays up. It looks like, from what they could tell, that people might be immune for years, and maybe even decades. That was really, really promising. It was excellent news. I wrote about that. I was so happy to write about it, because it was such great news.

Gus: If you get the vaccine, how long are you immune?

Apoorva: That's a very good question and one we're not really sure about yet. We're hoping that it will be years. If everything goes well, it will be years. But you might have heard that the virus is changing a little bit. It's possible that if people keep getting infected, lots of people keep getting infected, that the virus will change so much that we have to update the vaccine that we have now. That might mean that people have to get vaccinated again. That could be as soon as a couple of years. A lot depends on whether people are willing to get the vaccine quickly and a lot depends on what we find out about the vaccine as we keep going, because we've never had this vaccine before. We don't know how long it lasts.

Gus: If you know someone who got the vaccine, you still have to wear a mask around them, right?

Apoorva: They might not get sick, but they might still get infected and they might still carry the virus, and they might still give it to you. You do still have to wear the mask, unfortunately, until you yourself are vaccinated. If you're both vaccinated, then you might be able to leave that mask at home.

Gus: When do you think kids will get the COVID vaccine?

Apoorva: Usually what happens is, people test the vaccine in adults and then they test it in kids, because kids are not just mini-adults. They have to make sure that it works specifically in kids too. They can't just give a smaller dose. That's what they're doing now. They're starting to do those trials, and they'll probably have some data maybe in the late summer to early fall. It's going to take that long before kids get vaccines.

Gus: Do you think kids' lives will change when more adults get vaccinated?

Apoorva: Yes, things are going to be a lot more fun than they have been. Even if you're not vaccinated, you might get to go back to school, because teachers will be vaccinated, hopefully. You might get to see your grandparents, if you haven't seen them, you might get to see your friends more often, you might get to see relatives, and also all the grown-ups around you are going to be a lot less stressed out and a lot less anxious.

Gus: Okay, so what do you think this summer will be like?

Apoorva: Well, the summer, already, even last summer, I'm sure you noticed was a bit more fun, right, than when it's cold, because we get to be outside more, we get to see people more. That's going to be even better this summer because a lot more people will be able to get together both indoors and outdoors. I think really starting around late spring, once a lot of people have been vaccinated, things are really going to start to feel different. By summer, I think we're going to start to feel like, "Okay, we see the end coming now."

Gus: Okay, do you think that the vaccines that are already being made right now, at least in the United States, do you think those will protect against these new variants?

Apoorva: Yes. I don't think that we need to worry anytime soon that the vaccines will stop working. The virus is going to need to mutate a lot more before that happens. For the time being, we're good. These vaccines will work for quite a while.

Gus: Okay, that's pretty good news.


Molly: We're working on an episode about the science of love and crushes. We want to hear from you. We want you to describe what it feels like when you have a crush. Gus, what do you think? How would you describe what it feels like to have a crush on someone?

Gus: I feel like you might be asking the wrong person, but I don't know. From what I know, it's like you want to be near them and you feel happy when you're around them and when you see them, things like that.

Molly: Yes, that's a pretty good description of crushes I've had too. Listeners, send your answers to us at

Gus: While you're there, you can also send us mystery sounds, drawings, and questions like this one.

River: My name is River and I live in Oregon. My question is, what would happen if the moon fell down onto earth?

Molly: We'll answer that question during our Moment of Um, and we'll read the most recent group of listeners to be added to the Brains Honor Roll, all at the end of the show.

Gus: So keep listening.

Molly: You're listening to Brains On from American Public Media. I'm Molly.

Gus: And I'm Gus.

Molly: Okay, Gus, let's go back to that mystery sound, and let's hear it again.

(Mystery sound)

Molly: What are your thoughts after hearing it again?

Gus: Well, I mean, for most of it, I would definitely say like peeling off a lid or something but that thing at the end that's like crinkly almost. I'm not sure. Is it a lid made of cardstock?

Molly: You think it's a lid being peeled off of something? Potentially a lid?

Gus: Yes, probably, maybe protective plastic or something? Maybe cutting something.

Molly: I like it. Let's hear the answer.

Laura: Hi, my name is Laura and I live in Orlando, Florida. That was me opening a food can for my cat named fluffy.

Gus: Called it!

Molly: You did! Fluffy was getting dinner out of a little tin can. That was the sound of the lid being peeled off.

Gus: I have fed a cat before. Now that I think about it, it does kinda sound like that.

Molly: Yes, that's a very, very specific sound, really excellent guess, Gus. You have very good ears.


Molly: So far we've heard how the coronavirus vaccine was developed and how we know it's safe. Another thing scientists are looking at is how the virus is changing over time.

Gus: Brains On producer Menaka Wilhelm is here to explain what that means.

Menaka Wilhelm: Hello, yes, any changes to the coronavirus are good to know about. Scientists need to learn about them and understand what's going on, but they don't necessarily mean that we need to be extra worried. We definitely still need to wear masks, keep distance and wash our hands, because these are things that can stop the coronavirus no matter how it may change. It's normal for a virus to change over time. These changes are called mutations. A virus that has mutations is called a variant. Why is it so common for viruses to change? The coronavirus, like all viruses, has to copy itself a lot in order to spread, over and over and over and over again.

Lexi Walls: And sometimes it makes a mistake.

Menaka: Lexi Walls studies coronaviruses at the University of Washington.

Lexi: The majority of the time, those mistakes are bad, they actually don't help the virus.

Menaka: Some of the virus's copying mistakes do turn out to be helpful for it.

Lexi: Meaning that the virus is better able to survive, better able to transmit, better able to infect. When that happens, those viruses are much more likely to be able to make more of themselves and then go on to infect.

Menaka: We're seeing some variants like this in the world now, versions of the coronavirus that spread faster than previous versions. Spreading faster is not a good thing, but Lexi said even though these changes might make the virus spread faster, the vaccines we've got work well.

Lexi: You should still get a significant level of protection from these vaccines, which is awesome and is amazing to see.

Menaka: Let's say the virus changes enough that it could infect you even though you've gotten a vaccine. The good news is that the vaccination will still help you get less sick from it. These variants mean we need to keep doing what we've been doing, wear masks, keep our distance, wash our hands, and then get vaccinated when we can. We need to use all of the tools in our toolbox to stop this virus and luckily, the tools we have are good ones.

Gus: Thanks, Menaka.

Menaka: Of course. Bye.

Molly: Now, it's time for an answer to another listener question. This one is from Hunter in Schenectady, New York, who wants to know, what is herd immunity and how does it apply to the coronavirus?

Gus: Great question.

Kara: Move over Gus and Molly, we got this covered.

Gus: Oh wow. They're back.

Kara: That's right. I'm Kara.

Gilly: I'm Gilly and this is--

Kara and Gilly: Going Viral with Kara and Gilly.

Kara: Hi, your favorite viruses are back. Today, we're coming at you from somewhere new. Here's a hint. We're outside in a thicket of fur. I smell a mix of dirt and partially digested grass.

Gilly: We're on a cow!

Kara: Because today we're talking about something we've heard a lot about with this new coronavirus. It's herd immunity. Get it? Herd.

Gilly: Okay, Kara. New Year, same jokes, but yes, we're here at a herd of cows.

Kara: Gilly, as far as I understand, cows and humans are different species. Why should our human listeners care?

Gilly: Well, it does have to do with humans.

Kara: Oh, really?

Gilly: Yeah, remember, I sent you an email with our outline for today.

Kara: Gilly, I'm a fantastical virus with a great sense of humor and a brilliant podcast voice. Isn't that enough? You also expect me to read emails?

Gilly: Fine, I will text you next time. Anyway, herd immunity is the idea that if enough people are, ugh, immune to a disease, then the viruses that cause that disease won't be able to spread.

Kara: Okay, because if a virus tries to infect a new person but that person is immune and their body fights it off and that keeps happening, the virus will spread less and less and less and less?

Gilly: Yeah, until that virus becomes super rare. Kara, you okay? It's pretty heavy stuff to process. Kara?

Kara: Oh, hi. Yes, sorry. I just got distracted thinking about words to call a group of humans. So far, I got hoom boom, hoo bunch, and hoo many. Those are all way better than herd, right, which to my understanding is a word to describe a group of animals. Why is this called herd immunity and not, say, hoom boom immunity?

Gilly: I thought you would never ask. It's because the idea of herd immunity first came from veterinarians looking at diseases in cattle and sheep.

Kara: Of course, actual herds like this one.

Gilly: And then by the 1930s, people started to realize herd immunity also mattered for human diseases.

Kara: Okay. So what kind of diseases do humans have herd immunity against? Hopefully none of my friends.

Gilly: I don't know if you've met them actually, chickenpox, measles, mumps and polio are all viruses that used to cause a lot of disease.

Kara: Yeah, wow. I've only ever heard about those viruses.

Gilly: Humans made vaccines against them. With a vaccine, lots of people can get immunity without getting sick.

Kara: Oh, wow. They must be so excited that those new coronavirus vaccines could help build up herd immunity against the new coronavirus.

Gilly: Yeah. Honestly, I would love that too. I am so sick of that coronavirus hogging the spotlight, it is not the only virus.

Kara: I could not agree more. (buzzing) Gil, what is that?

Gilly: Okay. Stay calm, stay calm. It's a fly.

Kara: I have to get out of here. Cue the music, we are going home.

Gilly: Okay, that's it for the show this week. Remember, stay infecty.

Kara: And don't get sanitized!


Molly: Like really, how do Kara and Gilly keep getting on our podcast? Anyway, back to our episode. It is really exciting to think about what it will mean for our lives when more people have immunity to the coronavirus. That got Gus and I thinking about another virus, the one that causes the common cold. We asked Apoorva Mandavilli on our zoom call about it.

Gus: You know how the cold virus, how we don't have a vaccine for it, because it changes all the time. What makes a virus do that more or less?

Apoorva: A lot of it depends on the virus itself. Some viruses are just more prone to mutation than others. It also depends on how many people the virus infects, because the more people it infects, the more likely it is to change. The common cold coronaviruses are actually very similar to the new coronavirus. And I wrote a story that I think is very positive, which basically says that at some point in the future, all the adults will have had either the vaccine or will have had COVID and they'll all be protected.

As you know, kids don't really get all that sick with this virus. At some point, when enough people are vaccinated, we're going to get to a point where this new coronavirus is also going to be just like the common cold coronaviruses. It's going to be an annoying virus, but it's not going to be the scary, horrible thing that kills people.

Gus: Because the cold virus is such a common thing, is that why no one really gets seriously damaged by it, because we all get it so much?

Apoorva: Well, the theory, there's one very interesting theory about that. It's that in 1890, there was a pandemic and people thought it was a flu pandemic but possibly it was actually caused by one of the common cold coronaviruses that similarly affected adults really badly, but then all the adults got used to it, their bodies got used to it and now it really only affects kids under five. One of the reasons this virus is so dangerous is really because adults are just not used to fighting a new virus. Our bodies are better for fighting something we've seen before, whereas kids, especially young kids, up until 10, you're basically constantly fighting viruses and bacteria that your body has never seen before, so your bodies are really good at fighting new things.


Molly: Multiple coronavirus vaccines have been proven safe through clinical trials.

Gus: People across the country and the world are starting to get vaccinated.

Molly: Since these vaccines are new, we're not quite sure how long immunity to the virus will last if you've been vaccinated.

Gus: Scientists think that immunity to the virus after you've gotten sick from it, could last years or even decades.

Molly: As the virus continues to spread, it's changing a bit over time. Researchers think the vaccines will still work against these variants for a while.

Gus: Herd immunity happens when enough people have immunity against the virus, which makes it harder for a virus to spread.

Molly: That's it for this episode of Brains On.

Gus: Brains On is produced by Menaka Wilhelm, Marc Sanchez, Molly Bloom and Sanden Totten.

Molly: We had production help from Kristina Lopez and David Zha and engineering help from Andrew Walsh, who guessed the mystery sound right on his first try and Eric Romani. Our editor is Phyllis Fletcher. Many special thanks to Eric Ringham, Tracy Mumford Anna Weggel and Andy Ducett.

Gus: Brains On is a nonprofit public radio program.

Molly: You can support the show and help us keep making new episodes at

Gus: Now, before we go, it's time for our moment of um.

Listener: What would happen if the moon fell down onto Earth?

Smadar Naoz: First, I want to reassure that the moon is not going to fall down into the earth. The moon orbits the Earth every 29 days and it's about 239,000 miles away from us. In fact, it's also drifting away from us. Every year, it moves away from us at about 1.5 inches away. My name is Smadar Naoz, I'm a professor at UCLA. I'm a theoretical astrophysicist. We try to understand different puzzles that we see, different mysteries that we see and observe in the universe and in space around us. We use physics, which is the basic laws of nature, to try to understand the different mysteries that we observe.

If all of a sudden, for unexpected reason, which I cannot think what it will be, the moon will suddenly come closer, it can only come as close as 11,470 miles closer to us, before tidal forces will tear it apart. This is a special distance between us and the moon. It's called the Roche limit. This limit describes the distance for which a celestial object like the moon can hold together, so its own gravity will continue to hold it together and resist the gravitational forces that it feels from the earth.

Further away from these 11,000 miles, the moon will stay as the moon, but closer in, it will start to shatter and disintegrate and come to us in the way of rings. We will get rings. Just like Saturn has rings, we will get our own rings but these rings will be little chunks and pieces of rock just like in Saturn, they're little pieces of rock that will fall and rain on us on the earth. This is what will happen to the moon as it will come to us. It will disintegrate and we'll have rain of rocks coming in.

Before this will happen, tidal forces from the moon on the earth will cause big waves and tsunamis. We will have extreme climate conditions here on Earth before we will have the rain of rocks. Again I want to reassure everyone that the moon is not coming down on us.


Molly: I'm over the moon with this list, it’s time for the Brains Honor Roll.

(Honor Roll Names)

Molly: We’ll be back soon with more answers to your questions.

Gus: Thanks for listening!