Your vaccine questions, answered with Kizzmekia Corbett and Kelwalin Dhanasarnsombut

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0:58Try new Kashi Gut Health Granola. This episode is brought to you by Planet Visionaries, a podcast in partnership with the Rolex Perpetual Planet Initiative. Planet Visionaries is the podcast celebrating the people creating practical, hopeful solutions for our planet's urgent conservation challenges. Season 6 launches this fall with bold, real solutions. Hear from Anna Rathman of the Jane Goodall Institute on protecting wildlife. Tom Pesach on his 396-day journey documenting the entire Amazon. And Lydia Oshie, a Guatemalan leader opening doors for Indigenous girls to access global education. Hosted by legendary climber and advocate Alex Honnold, each episode goes beyond the headlines to show what's actually working and who's making it happen.

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1:58This is TED Health, a podcast from TED, and I'm Dr. Shoshana Ungerleiter. I'm a board-certified practicing internal medicine physician, and I'm your host for today's show. I'd say that we live in one of the safest eras of all of human history. You get into a car and you click on a seatbelt. You open a carton of milk without wondering whether it's been pasteurized. You order lunch and assume someone, somewhere, has been paying attention to whether that food is safe to eat. And when those systems work, nothing memorable happens. You arrive, you eat your lunch, you go on with your day. We live inside all of these layers of protection that, when they're working well, barely register.

2:42We move through them every day without really noticing them. And I find that kind of remarkable. Especially because when we're able to take these safety measures for granted, it means they're working. For me, this is one of the miracles of modern medicine. There's no photograph of a preventable illness. Because it didn't happen. No family story about the hospitalization that was completely avoided. And that creates an interesting paradox. The better that prevention works, the harder it can be to remember what we were preventing in the first place. And I wonder if that's part of what makes vaccines so unusual.

3:21When prevention works across generations, eventually we lose the memory of what came before it. The danger starts to feel abstract. The protection can start to feel optional. For children born in the U.S. between 1994 and 2023, the CDC estimates that routine childhood vaccination will prevent more than a million deaths over their lifetimes. That number is almost impossible to picture. For most of us, a vaccine feels much smaller. It's a doctor's office, a sore arm, maybe a Band-Aid and a sticker, and then you go home. So how does that small moment create protection that can last for years, or sometimes decades?

4:06That brings us to a classic 2015 TEDx lesson about what vaccines are actually asking the immune system to do. The lesson begins with Edward Jenner in 1796, and then moves through our immune system's remarkable ability to remember a threat before we encounter the full-strength disease. It also captures a moment in the history of vaccine science. Near the end, the lesson imagines a future when vaccines might help protect us against malaria or Ebola. And some of that future has already arrived. Stick around and I'll share some more after the lesson. And now your TED-Ed lesson of the day. In 1796, the scientist Edward Jenner injected material from a cowpox virus into an 8-year-old boy with a hunch that this would provide the protection needed to save people from deadly outbreaks of the related smallpox virus.

5:01It was a success. The 8-year-old was inoculated against the disease, and this became the first-ever vaccine. But why did it work? To understand how vaccines function, we need to know how the immune system defends us against contagious diseases in the first place. When foreign microbes invade us, the immune system triggers a series of responses in an attempt to identify and remove them from our bodies. The signs that this immune response is working are the coughing, sneezing, inflammation, and fever we experience, which work to trap, deter, and rid the body of threatening things like bacteria. These innate immune responses also trigger our second line of defense, called adaptive immunity.

5:48Special cells called B cells and T cells are recruited to fight microbes and also record information about them, creating a memory of what the invaders look like and how best to fight them. This know-how becomes handy if the same pathogen invades the body again. But despite this smart response, there's still a risk involved. The body takes time to learn how to respond to pathogens and to build up these defenses. And even then, if a body is too weak or young to fight back when it's invaded, it might face very serious risk if the pathogen is particularly severe. But what if we could prepare the body's immune response, readying it before someone even got ill?

6:34This is where vaccines come in. Using the same principles that the body uses to defend itself, scientists use vaccines to trigger the body's adaptive immune system without exposing humans to the full-strength disease. This has resulted in many vaccines, which each work uniquely, separated into many different types. First, we have live, attenuated vaccines. These are made of the pathogen itself, but a much weaker and tamer version. Next, we have inactive vaccines, in which the pathogens have been killed. The weakening and inactivation in both types of vaccine ensures that pathogens don't develop into the full-blown disease.

7:15But just like a disease, they trigger an immune response, teaching the body to recognize an attack by making a profile of pathogens in preparation. The downside is that live attenuated vaccines can be difficult to make, and because they're live and quite powerful, people with weaker immune systems can't have them. while inactive vaccines don't create long-lasting immunity. Another type, the subunit vaccine, is only made from one part of the pathogen, called an antigen, the ingredient that actually triggers the immune response. By even further isolating specific components of antigens, like proteins or polysaccharides, these vaccines can prompt specific responses.

8:01Scientists are now building a whole new range of vaccines called DNA vaccines. For this variety, they isolate the very genes that make the specific antigens the body needs to trigger its immune response to specific pathogens. When injected into the human body, those genes instruct cells in the body to make the antigens. This causes a stronger immune response and prepares the body for any future threats. And because the vaccine only includes specific genetic material, it doesn't contain any other ingredients from the rest of the pathogen that could develop into the disease and harm the patient.

8:37If these vaccines become a success, we might be able to build more effective treatments for invasive pathogens in years to come. Just like Edward Jenner's amazing discovery spurred on modern medicine all those decades ago, continuing the development of vaccines might even allow us to treat diseases like HIV, malaria, or Ebola one day.

9:03This TEDx lesson was created by Gaywaleen Tanassansambat, directed by Veronica Wallenberg, edited by Emma Bryce, and narrated by Addison Anderson. This lesson was published in 2015. Today, we have two WHO-recommended malaria vaccines and a licensed vaccine that protects against one type of Ebola virus. I love this lesson because it's a helpful primer in a vital part of health science, but it's also a reminder to keep things in perspective. What sounded like a mere possibility about a decade ago has quietly become medicine today, and I can only imagine what we'll accomplish 10 years from now. But when it comes to vaccines, biology is only part of the story.

9:48A vaccine can teach the immune system what to recognize. It can't, by itself, answer the questions that someone brings into a clinic, or the worry that a parent carries after reading a frightening headline late at night. Dr. Kismikia Corbett knows both sides of that story unusually well. At the National Institutes of Health, she helped lead the scientific work that contributed to Moderna's COVID-19 vaccine. And now at Harvard, she's thinking just as seriously about another problem. What happens when people are uncertain about vaccines? She calls it vaccine inquisitiveness. And I like that phrase because it makes room for curiosity.

10:27It's important to remember that not every question is rejection. Not every concern means someone's hostile to science. Sometimes a person is simply trying to make sense of risk. And what happens next may depend on whether they feel dismissed or heard. Science can make extraordinary tools. Trust develops differently.

10:52And now Kismikia Corbett.

10:55Kizzmekia Corbett: So in summer 2018, I went on a first date. Now in my early 30s, this of course was not my first first date. And so I wasn't expecting much except for some beers and tacos. That was until I was too many beers in and too deep in conversation. My question to him at the end of the night, do you plan to vaccinate your kids?

11:22Kizzmekia Corbett: His reply, sure. except for the flu vaccine, because the flu vaccine has viruses in it. And every time I take it, I get sick. I guess he didn't realize that he was sitting across the table from a woman who had just invented a novel flu vaccine that was then slated for clinical trial. But at the same time, I was a research fellow at the National Institutes of Health Vaccine Research center. And so normally that answer would have sent me packing on to my next first date, but I like this guy. And so I stayed and I answered a few questions after getting another beer. I told him that yes, the flu vaccine does have viruses in it, but those viruses are not alive, and so they technically cannot make you sick.

12:12Kizzmekia Corbett: Sure, you may feel a little groggy after getting the shot, but that's just a sign that your immune system is working. And I asked him a simple question. Did he know that there are 200 or more viruses that can cause flu-like symptoms or the common cold? Of course, he didn't have an answer, but that's what you get when you take a vaccinologist on a date. Surprisingly, he was not offended, and he asked me out on a second date. And I got more than a second date out of this guy, I got my first understanding of what I now like to call vaccine inquisitiveness. It wasn't that he was just reluctant to get himself vaccines or to get his future children vaccinated.

12:58Kizzmekia Corbett: It was that he had questions, concerns, misinformation buried deep down for which he needed an expert like myself to answer without scorn and without judgment. it. Nevertheless, I went back into the lab and I did what I do, making vaccines. And then on December 31st of the next year, there was a report of a mysterious virus in Wuhan, China. It had sickened 27 people. This was a moment that my team had prepared for. You see, not only was I on the flu team, but I was also the scientific lead of the coronavirus vaccine team.

13:41Kizzmekia Corbett: You see those orange proteins on the surface of this coronavirus? Those are called spike proteins, and those proteins are responsible for driving immunity. So we developed a spike protein with a small sequence change that made it an ideal vaccine candidate in case of a pandemic. And that's exactly what happened. In January of 2020, that virus that was circulating was deemed to be a coronavirus. We joined forces with Moderna and we promised ourselves that we were going to get in a phase one clinical trial in only 100 days. A purely scientific goal, by the way, but as I look back and I write this speech, I think there was probably a little bit of ego attached to it too.

14:25Kizzmekia Corbett: But that's okay because we did it. I mean.

14:35Kizzmekia Corbett: After countless hours in the lab, testing that vaccine in mice and monkeys and determining that it was safe and effective enough to go into humans, that vaccine, mRNA-1273, or what you now know to be called SpikeVax, went into a phase one clinical trial in only 66 days, a world record. Now, at the end of the year, that vaccine was determined to be 94 % effective against disease. So we were proud of ourselves, obviously. But what was the gut punch for me was that 20 % of people were what the WHO would call vaccine hesitant. Now, vaccine hesitancy is not new. Even prior to the pandemic, vaccine hesitancy was deemed to be one of top 10 global health threats.

15:27Kizzmekia Corbett: Top 10 global health threats, and that is something that even me making vaccines was not going to fix. And the truth of the matter is that vaccinologists like myself had long ignored this population of people who just were not going to take vaccines for one reason or the other. We were too busy publishing our data in world-renowned journals, kind of talking to ourselves. And the other truth of the matter is that we made some honest communication mistakes during the pandemic. And I'll be the first to just talk about myself. The first time I got on TV, I said that the vaccine was going to curb transmission.

16:05Kizzmekia Corbett: And at that time, it did. But what I should have said is that over time, as the virus mutates, the vaccine may not be as good at covering transmission. And then we should have taken just a little bit more care and tenderness to talk to people about the possibility of vaccine injury. Even if vaccine injury didn't turn up in our clinical trials, there was always this possibility. And those types of stats didn't matter to someone who was reading headlines about vaccine injury. and deciding whether they were going to get themselves or their loved ones vaccinated. You see, some people had questions and concerns that were genuinely valid.

16:49Kizzmekia Corbett: And some people actually had criticisms that were genuinely valid too. Except for that one time the internet went ablaze when they said my hair was ugly on CNN. I like to think that I'm pretty cute.

17:05Kizzmekia Corbett: Seriously though. So one of the major concerns was that we were moving too fast. And so I'm going to stand right here in the middle of this TED circle and say, there was so much research that was done prior to the pandemic. People studied coronavirus' basic biology. The Nobel laureates studied how to make mRNA feasible to deliver medicines into the body. We even did our thing too. Nevertheless, all of that research pushed the coronavirus vaccine out quicker, safer, and more effective. All of that notwithstanding, some people still had questions that needed to be answered. Some people were still vaccine inquisitive.

17:48Kizzmekia Corbett: No, they were not anti-vax, and no, they weren't even anti-science. They were unconvinced. And it was our job as scientists to make them convinced. except that failed communication lingered on, and I'm afraid that maybe some of that failed communication is the reason why today we have a rise in vaccine refusal. Kindergarteners are showing up to kindergarten without their full vaccine regimens. Measles is on the rise in many communities, and measles, by the way, is a vaccine-preventable disease. And for me, that's really unfortunate because I know that there are 23 viral families that have the potential to infect humans.

18:36Kizzmekia Corbett: So it's not a question of whether there will be another pandemic. It's a matter of when. And so I guess I'm lucky because I will always have a job, but as a vaccine inventor at Harvard University, my lab studies how to make nanoparticles or small protein balls into vaccines. We put viral proteins on the surfaces of those nanoparticles, kind of in a click and bait way, with small linkers that allow us to drive those viral proteins directly to the cells in the immune system that we need to make ideal vaccines for pandemics. We can put just about any type of viral protein on the surface, many of them at the same time, so that we can make vaccines that are hypothetically good against many viruses in one shop.

19:23Kizzmekia Corbett: Great. Vaccine technology is going to go on and on and on. But I like to believe that vaccine hesitancy does not have to go on and on and on with it. If researchers would just open their minds to vaccine inquisitiveness in the same way that we open our mind to scientific inquisitiveness, if community and science were to meet. And that's not really that revolutionary. We already know that when community and science meet, science advances faster, vaccine refusal turns into vaccine acceptance. Actually, when vaccine inquisitive meets a scientist on a date, it turns into a marriage.

20:10Kizzmekia Corbett: You know, one thing about this is that my husband still has questions every single time we take our children to get their vaccines. And I still have to find the answers, not just as a scientist, but now as a mother, because I'm concerned about my children's safety and my children's lives depend on it. Thank you.

20:39That was Dr. Kizmekia Corbett at the 2026 TED conference. And that's our show for today. Thank you so much for listening. TED Health is a podcast from TED, and I'd love to hear your thoughts about this episode. Send me a message on Instagram at ShoshanaMD. This episode was produced by me, Shoshana Ungerleiter, and Jess Shane. Edited by Alejandra Salazar and fact-checked by Vanessa Garcia-Woodworth. Special thanks to Maria Lajas, Farah Degrange, Daniela Balarezo, Constanza Gallardo, Tansika Sangmarniwang, and Roxanne Heilash.

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