This is a transcript of our episode “What's in the COVID vaccine?”

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

Kara: Oh, it’s perfect, they haven’t started yet.

Gilly: Ok, quick, let’s get going before they do! 

Kara: I’m Kara

Gilly: And I’m Gilly

Kara: We’re two viruses with a dream and a microphone --

Gilly: We share it.

Kara: That’s right -- this is…

Kara and Gilly: Going viral with Kara and Gilly!

(KARA and GILLY music)

Kara: Ok, hoombooms, we’re not going to do our usual top of the show chitty chatty catchy uppy because -- I never thought I’d say this -- but we don’t need any more attention.

Gilly: Now, we love the sounds of our voices as much as you do --

Kara: (singing) Our voices are like beautiful baby birds...

Gilly: ok, yeah, they get it, Kare Bear. Anyway, viruses are getting too much attention these days. Everyone’s out here giving tips on how to sanitize!

Kara: Ugh!

Gilly: How to mask and stay distant so we can’t spread!

Kara: Gross!

Gilly: Making new vaccines to fight us!

Kara: The worst!

Gilly: And studying us more to learn our deepest, darkest secrets.

Kara: Those aren’t for you!

Gilly: Yeah -- it’s not great. So we’re gonna step back from the pod for a bit…

Kara: Do all that self care stuff we’ve been putting off -- you know just taking care of us for a while?

Gilly: Yeah, but don’t worry -- we will be back! Refreshed and renewed and focused on how to get our viral message out to the world.

Kara: But thanks for listening, viralinos! We couldn’t do it without you!

Gilly: Until we get back, you can support us on our ickstarter!

Kara: Or not. We just appreciate you. For real, we love you viralinos.

Gilly: And remember --

Kara: Stay infecty!

Gilly: And don’t get sanitized!

Gilly: Ok, if you put the Brains On music now they’ll never know we were here. 

Kara: Smart.

(Brains On theme music)

Molly Bloom: You're listening to Brains On! from American Public Media. I'm Molly Bloom, and my co-host, once again, is Gus from Seattle. Hi, Gus.

Gus: Hello.

Molly: We know some of our listeners are back in the classroom after a long time of not being in the classroom, and others are back on lockdown. Depending on where you live, things can feel pretty different right now. Gus, how would you say things are feeling in Seattle?

Gus: They're feeling pretty good. It's definitely very cold. We got like a foot of snow the other day. I feel like things are better than before, but we're still online. I went sledding the other day, obviously, because it's a foot of snow, and I've also been feeding the crows a lot.

Molly: What about it feels better than before?

Gus: I feel like I'm not as panicked as before. I wasn't that worried before, but it just feels better now.

Molly: Do you think you can pinpoint that to something happening?

Gus: Probably the vaccines made it feel a lot better.

Molly: It sort of feels like something's happened, something is changing. It's not just the same never-ending waiting that was going on before.

Gus: Yes.

Molly: This moment has felt hard for people because vaccines have been approved, but it's still going to take several more months before everyone who wants one is able to get it. There is a light at the end of the tunnel, but we're just not out of it quite yet. My husband described it like this. You're on a plane and the plane has landed, but you're just sitting on the runway waiting for a gate to open up so you can get off the plane.

People are getting pretty antsy because they just want to get to the gate. Some people are trying to stand up but the flight attendant is on the speaker asking people to stay seated and keep their seatbelt on until we actually get to the gate and the door opens. I think that's pretty accurate. It's kind of what it feels like for me right now. Does that ring true for what it feels like for you, Gus, or does it feel different than that?

Gus: Yes, that sounds accurate. You know how sometimes when you get up in the morning your feet or your legs are all tingly, and it's hard to walk and stuff but you have to wait an hour for them to start working good? Kind of like that.

Molly: Yes, I can see that. It can be hard, but like we talked about back in October, this is a historic time we're all living through, and people all over the world are being affected by it. Many of us have lost loved ones, and many people are experiencing grief, which is how we describe the big feelings that come with big loss.

Gus: You're not going through this alone. Remember that we're all living through something that our parents and grandparents have never gone through before.

Molly: It's been just about a year. We've had a pandemic version of every holiday.

Gus: Everyone has had a pandemic birthday.

Molly: Some of us are coming up on our second pandemic birthdays.

Gus: This is not the year anyone was planning for.

Molly: You've done hard things this year, and we're really, really proud of you.

Gus: Even though this has been going on for a year, we still have a lot of questions, and you do too.

Molly: We're going to start by answering this one.

Oliver: Hello, my name is Oliver from Baltimore, Maryland. My question is how does the COVID-19 vaccine work and what is its side effects?

Gus: Brains On! producer, Menaka Wilhelm, is here to take a peek inside.

Menaka Wilhelm: Hello. To answer that question we're going to need to zoom.

Gus: Like video Zoom, another call?

Menaka: Oh, thankfully no. We have plenty of that kind of Zoom these days. We're going to be zoom ray zooming. Zoom ray ready. Zoom, zoom. Perfect. Before we zoom, a quick recap of how these vaccines work.


Molly: Vaccines help protect your body against germs by exposing your immune system to a tiny bit of a germ or a weakened version of it. Your body sees this tiny harmless version of the germ and learns how to destroy it without you getting very sick from it.

Gus: Then if your body ever encounters the real version of the germ, your body remembers it and is ready to fight it off right away.

Menaka: Without a vaccine, your body takes a while to recognize the germ and then fight it off, and in that time, you might get sick. That's why vaccines are terrific. They give your body a practice run at handling a germ. Your immune system learns what to do, and you don't get super sick.

Gus: That's what the COVID vaccines do. The two that have been approved in the US so far are a kind of vaccine called mRNA vaccines.

Molly: The M in mRNA stands for messenger. These vaccines carry a message that tells your cells to make a tiny protein found on the spike of the coronavirus.

Menaka: When your body sees these spike proteins, it fights them off and develops antibodies against them.

Gus: If the real coronavirus shows up in your body, your immune system will remember those proteins and attack the virus before it has a chance to make you very sick.

Molly: Meanwhile, once your body gets that message, the mRNA from the vaccine gets destroyed. We use mRNA for all kinds of stuff in ourselves, and we have special proteins that break down mRNA into tiny little bits.

Menaka: Are you ready for something really cool? These vaccines are designed to give you a better immune response than the one that you'd have against an infection, so when you get a vaccine you're prepared in a turbocharged way. That's also why the vaccines are even helpful for people who might have already had COVID-19. Cool, right?

Gus: Super cool.

Menaka: Another cool thing is that mRNA is teensy, teensy, teensy tiny, so how do they get it in the vaccine? Let's find out. We'll zoom in on this glass vial of the vaccine. [clicking sound] Ready?

Gus: Yes.

Recording: Zoom, zoom, zoom, zoom, zoom, zoom, zoom, zoom.

Menaka: You can see this vial is full of liquid, and in the liquid is itty bitty vaccine mRNA. The mRNA is all wrapped in tiny fat bubbles. Those bubbles protect it in its journey into your cells.

Gus: Like bubble wrap?

Menaka: Precisely. The tiny fat bubbles are like a really special version of bubble wrap, and they're protecting a pretty fragile molecule; that's the mRNA. It needs to be in tip-top shape when it's time to tell yourselves what to do.

Molly: Anything else in there?

Menaka: Besides the fat bubbles and the mRNA, there's a little bit of water and a tiny bit of sugar, and some special salts and acids. Sugar keeps the fat bubbles from sticking together, and then the salts and acids make sure that the vaccine blends in well when it gets into your body. Our insides are salty. Are you ready to zoom in on that mRNA itself?

Molly: Sure.

Recording: Zoom, zoom, zoom, zoom, zoom, zoom, zoom, zoom.


Menaka: All right. The mRNA, the crown jewel of this vaccine.

Gus: Wow. This little string of molecules tells your body to make coronavirus spike proteins?

Menaka: Yes, and it came from a super clean vaccine-making factory. Vaccine makers cook up this mRNA in bucket-shaped vats. Actually, it only takes a tiny bit of mRNA to make each vaccine dose, so those vats aren't necessarily that big. Some hold around 10 gallons, which is about the size of a fish tank. A vat that size holds the recipe for many, many doses of the vaccine.

Molly: I bet that's quite a recipe.

Menaka: Definitely. Not quite as delicious as Baked Alaska, but certainly as complicated. Making a vaccine is a little bit less hands-on than making a cake at home. Scientists and engineers have set up this vaccine recipe so that lots of stuff happens because of machines and molecules.

Gus: So scientists aren't stirring up batches of vaccines one at a time?

Menaka: Nope. Using machines and molecules more than human hands makes things go faster. It also keeps everything cleaner. Inside those vaccine-making vats, scientists use enzymes, which are special proteins, to make the mRNA from its ingredient molecules. The raw materials for mRNA are these molecules called nucleotides. In one of those vats, they mix together nucleotides, enzymes, and other compounds that help the enzymes do their job. Then enzymes do the work of putting the mRNA together because that's just how those enzymes react with all of those other ingredients.

It's a little bit like how when you put a cake into the oven, your cake starts out as a liquid and then over time becomes a cake. All thanks to the way that those ingredients react together.

Molly: How long does it take to make that recipe of mRNA?

Menaka: Making the mRNA takes a little bit less than a week, which sounds really fast, but that's just one part of making the vaccine. There's also a lot of steps to set up the mRNA recipe, and then after the mRNA is done, special mixers whip everything up so that you get those tiny fat bubbles around the mRNA.

Gus: Of course, the vaccines also have to go into their little vials.

Menaka: Of course. Also, a really big part of this process is double-checking mixtures and machines at different steps. Vaccine makers follow a bit of their recipe and then double-check it before they move on. The double checks often take longer than the recipe steps, but that's a good thing overall. It's super important to be sure that every part of this process is happening exactly the way that it's supposed to.

Gus: That's why it takes a couple of months to get those batches of vaccine from start to finish?

Menaka: Exactly. The batches are pretty big, like millions of doses. Speaking of big, are you ready to zoom back out?

Molly: Yes.

Recording: Zoom.

Menaka: Nothing like the zoom ray. These mRNA vaccines are pretty clever. They use a messenger molecule that our bodies know really well to teach us how to fight off the coronavirus. But there are other vaccines coming out soon too.

Molly: They use slightly different tools to train your body, so the recipe for each vaccine is a little different.

Menaka: For each vaccine, scientists have set up a super special recipe. They've got molecules that will react to make bits of the vaccine that they need, and then machines that mix and separate and package the vaccine safely. Setting everything up to make these vaccines is definitely a big process, but people are working on it around the clock every day.

Gus: Thanks, Menaka.

Menaka: Nice zooming. Bye.

Recording: Ba, ba, ba, ba, ba, ba, ba, ba, ba Brains On!

Molly: Okay, Gus. Here's something we don't need a zoom ray to understand. It's time for the--

Recording: Mystery sound.

Molly: Here it is. (sound) All right, Gus. What is your guess?

Gus: I think maybe like reeling in a fishing rod or something.

Molly: Mmm. Really nice guess. What about the sound made you think that?

Gus: I thought I heard the wind, so I thought they were outside. I heard the clicking and the spinning of the lever that you pull.

Molly: We'll be back with the answer and give you another chance to guess a little later in the show.


Gus: We're working on an episode, all about time travel, and we want to hear from you.

Molly: If you could time travel to any time past or future, when would it be? Gus, what do you think? When would you travel to?

Gus: I would probably travel to right now because I wouldn't want to start a space-time continuum.

Molly: You're worried about the ramifications of time travel?

Gus: Yes. I don't want to tear the very fabric of the universe.

Molly: Okay. Life. Life. Record your answer and send it to us at

Gus: While you're there, you can send us your questions, mystery sounds, and drawings too.

Molly: That's where we got this question.

David: Hi, my name is David.

Emmett: I am Emmett.

David: We're from Boston, New York, and we are wondering--

Emmett: What foods do the scientists in Antarctica eat?

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

Gus: Keep listening.


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

Molly: And I'm Molly. It's time for us to answer this question.

Liron: My name is Liron from Maryland. My question is, does the COVID-19 vaccine protect people against all new viruses too?

Katherine Wu: Yes. It's a good question, and actually a really complicated one.

Gus: That's Katherine Wu.

Molly: She's a science journalist for The Atlantic.

Katherine: I'd say at this point there's not really evidence for that yet. Not because there's evidence of the absence of that happening, but just because people haven't really been looking. All the focus has been on whether these vaccines prevent the disease that they were designed for, which is COVID-19.

Molly: It's become very clear that the other tools we've been using to fight the coronavirus-

Gus: Distancing, staying home, wearing masks, washing your hands.

Molly: -have definitely been protecting us against other viruses.

Gus: Hardly anyone has gotten sick with the flu this year.

Molly: Fewer people are getting the rhinoviruses that cause colds too.

Katherine: It's just been this giant natural experiment that I think people are going to be studying for years and years and years to come.

Gus: But it doesn't mean we're done with the flu forever.

Molly: The virus is still out there, and eventually as we're masking and distancing less, more people will start getting the flu again.

Katherine: When flu viruses do come back, we can think back to this year and think about how effective it is to wash your hands, [chuckles] how effective it is to put on a mask when you're feeling not well, or when you're worried that you're going to be in a group of a lot of people, and there are viruses circulating around. How important it is to stay home when you're not feeling well, and that you can protect not just you but the people around you by staying away when you know that there's an infection circulating around.


Molly: Okay. Gus, are you ready to go back to that mystery sound?

Gus: Yes.

Molly: All right. Here it is again. (sound) All right, Gus. Any new thoughts? Last time you thought it was reeling in a fishing line.

Gus: Yes. I think that's still the best guess I have.

Molly: All right. Well, let's hear the answer.

Clara: Hi. My name is Clara and I'm from Vienna, Virginia. That was the sound of me casting out a fishing line and reeling it back in. I recorded that sound in a rowboat on Swagger pond in Pennsylvania. I like to fish from a rowboat or the dock, or maybe even sometimes a stand-up paddleboard. If you get hot you can dive into the water and swim around.

Gus: Yay. I'm still on my win streak.

Molly: Yes, you are. That was really impressive. I thought maybe it was like a scooter or something. I was not close to that at all.

Gus: I only have three more guesses to get right until I get to go to the mystery sound factory.


Molly: As of February 22nd, over 19 million people in the US have been fully vaccinated.

Gus: Right now two vaccines are approved in the US, and more are likely to be approved in the coming weeks and months.

Molly: As scientists and journalists and politicians talk about how well these vaccines work, a lot of numbers get thrown around, and it's difficult to understand them.

Gus: We talked to someone who can help us get answers.

Maria Sundaram: My name is Maria Sundaram. I'm an infectious disease epidemiologist, and I'm also what's called a postdoctoral fellow at the University of Toronto.

Molly: Let's take the Pfizer mRNA vaccine as an example. It's said to be 95% effective.

Gus: You might think that means it protects 95% of the people who get the vaccine.

Molly: Or you might think that you have a 5% chance of getting COVID if you get the vaccine, but that's not it at all. For a vaccine that's 95% effective, the numbers show that just a fraction of 1% of people who are vaccinated got sick. Way less than 5%.

Maria: We're talking about the number of people who might get sick among the people who do get the vaccine and people who don't get the vaccine. 95% of the cases that would have happened in the group of people who didn't get the vaccine didn't happen in the group of people who did get the vaccine.

Molly: This means if you get the vaccine, you're 95% less likely to get COVID than someone who didn't get the vaccine.

Gus: This kind of math is called statistics, and it's a little bit tricky to wrap your head around.

Molly: When they did the clinical trial for the vaccine-

Gus: Listen to our last coronavirus episode for more on the clinical trials.

Molly: -they gave half of the people in the trial the actual vaccine, and the other half got a placebo, which is a shot designed to do absolutely nothing. It's made of saltwater.

Gus: The scientists running the clinical trial closely monitor how these volunteers are doing.

Maria: Yes. Normally when you sign up to be a participant in a clinical trial, you get a diary that they ask you to write down basically how you're feeling as often as possible. Sometimes this is daily, sometimes it's weekly, but they want you to write down, "Hey, I have a slight headache today," or, "Hey, I'm feeling a little feverish today," or, "Hey. Today I'm great and there's nothing wrong with me at all." When we do clinical trials we're very closely following how people are feeling and how they're doing for quite a long time.

We're even asking people months and months later, "Hey, how are you still doing? How was that second dose for you? I know it's been three months since you got the second dose. How are you feeling today?" That kind of stuff is really, really important because we not only want to know about the safety and effectiveness in the shorter term around when we're getting the vaccine, but we also want to know long-term is it helping you, and also, are you still feeling good?

Molly: Let's go back to that 95% number and see where it comes from.

Gus: There were about 42,000 people in the Pfizer trial.

Molly: Imagine a stadium full of people.

Gus: Half the stadium is wearing purple jackets representing the vaccine team. [noisy fans]

Molly: The other half of the stadium is wearing yellow jackets representing the placebo team. Now, there was one of those giveaways today at the game where everyone gets cool swag to rep their team.

Gus: The vaccine team got awesome purple umbrella hats to match their jackets. You know those tiny little umbrellas that sit on your head? They're adorable.

Molly: The placebo team got sweatbands. A good look, but no real protection for their heads.

Gus: Okay, so this stadium is near to the ocean, and there's a lot of seagulls flying overhead.

Molly: When they're flying, sometimes seagulls poop. For our analogy, seagull poop is like COVID.

Gus: During the game, 172 fans of the placebo team, the ones wearing the stylish yet ineffective sweatbands, got seagull poop on their heads because the sweatbands didn't do anything. That's like six rows of stadium seats full of people who got poop on their heads.

Molly: But the lucky vaccine team with the beautiful purple umbrella hats, those hats actually covered their heads. Only nine of them got poop on their heads. That's nine people out of 21,000 team vaccine fans,

Gus: Less than one row of seats. Those umbrella hats really work.

Molly: A total of 181 people got seagull poop on their heads during the game, and 95% of them were wearing the team placebo sweatbands. That’s where we get that 95% number. Scientists use that same math for all the vaccines.

Gus: Remember, behind all of these statistics are real people.

Maria: Tens of thousands of people agree to be participants in these clinical trials. That made the enrollment for the clinical trials really fast, and that’s really, really, really incredible. If people said, "No, I don’t want to be a part of this," that would have meant that we would have waited a lot longer for a vaccine.


Gus: We're all in this pandemic together. We're still living through history.

Molly: We're keeping our distance, wearing masks, and staying home.

Gus: Because we know those things work against the coronavirus. They've lowered flu cases too.

Molly: Some things are starting to change a little. More people are getting vaccinated every day.

Gus: The two vaccines that have been approved in the US use mRNA to give your body practice fighting the coronavirus.

Molly: Beside that mRNA, the vaccines contain tiny fat bubbles, sugar, water, and a couple of salts and acids.

Gus: We know those vaccines work, and that they’re safe.

Molly: Because thousands of people volunteered to be in clinical trials, and scientists studied the vaccines very closely. That's it for this episode of Brains On!

Gus: It was produced by Marc Sanchez, Menaka Wilhelm, Sanden Totten, and Molly Bloom.

Molly: We had production help from Kristina Lopez and David Zha, editing from Phyllis Fletcher, and engineering help from Jay Follette at Avast! Recording Company, and Cameron Wiley. Special thanks to Anna Weggel, Tracy Mumford, Prashant Yadav, Dave O'Connor, Natalie Dean, Vikki Krekler, and Coco.

Gus: Now, before we go, it's time for our Moment of Um.

Multiple Speakers: Um.

Cameron Hearne: What foods do the scientist in Antarctica eat? The short answer is that the food that the scientists eat down in Antarctica is very similar to what you eat here, but it’s mostly preserved food, so what you would find in your pantry.


Cameron: Hi. My name is Cameron Hearne, and I’m a scientist who went down to Antarctica. In Antarctica, I was looking at how climate change was affecting the growth of bacteria in the ice-covered lakes. On a typical day in Antarctica, for breakfast I would have oatmeal and a Snickers bar, and then for lunch, I would have a peanut butter and jelly sandwich and a Snickers bar. For a snack, I’d have another Snickers bar, and then for dinner, I would have pasta followed up with a Snickers bar. [laughs] We had an allotment of four, five Snickers bars today per person.

I was eating so many Snickers bars because it was important to try and stay warm. To stay warm when it's negative 20 degrees outside you have to eat a lot of calories, and Snickers bars have a lot of calories for how big they are. No veggies are required, basically, but you do have to get nutrients in some way, so pasta sauce or Hi-C is also a good one. The food comes from a big ship that comes in once a year and drops off all of the food we'll eat through the winter and through the summer.

Every once in a while, freshies or fresh vegetables and fruits will get flown in from New Zealand. It's so rare that it comes in maybe about once a month, and during the winter no planes and no ships come in. They're just left with the food they have. Because of how the food gets down there, and it's stored for so long, the vast majority of the food is well beyond the expiration date. Some foods taste a little different, but for the most part, it’s about the same. The food down in Antarctica isn’t bad, but it doesn’t beat the cherished food that's back home.

Multiple speakers: Um.

(Honor Roll Names)

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

Gus: Thanks for listening!