Melanie Cole, MS (Host): There's no handbook for your child's health, but we do have a podcast featuring world-class clinical and research physicians covering everything from your child's allergies to zinc levels. Welcome to Kids Health Cast by Weill Cornell Medicine. I'm Melanie Cole. And joining me today to give us some vaccination guidance for vulnerable babies and children is Dr. Sean Cullen. He's an Assistant Attending Pediatrician at New York Presbyterian Hospital Weill Cornell Medical Center and an instructor in Pediatrics at Weill Cornell Medical College Cornell University.

Dr. Cullen, thank you so much for joining us today. Can you tell us a little bit to begin about vaccine-preventable diseases and how we have, with vaccines, eradicated some of the worst diseases we've ever seen.

Dr Sean Cullen: Of course. So, I think the first thing to start off with is just a discussion of what vaccines are. So in general, they're a tool that pediatricians use to basically help teach someone's immune system, which is specifically their white blood cells, how to kind of fight off a particular infection, whether that's from a virus or bacteria. Vaccines use something called antigens, which are basically just specific parts of various bacteria and viruses that help your immune system recognize those infections and then develop a defense system to fight off those infections in the future. This defense system is something called antibodies, and they're just very specialized proteins that can either help prevent a disease, infection occurring altogether or reducing the really severe symptoms of those infections.

So, this is how our body normally responds to infections, and vaccines are basically just a way to give that immune system the best possible chance of stopping that harmful bacterial or viral infection in its tracks. So, kind of thinking of some of the vaccine success stories that we have had. I think one of the best illustrations for that is actually the polio vaccine. So, polio is a virus that is very highly contagious. It's able to enter our central nervous system, so our brain and our spinal cord, and infect those specific cells, oftentimes with, unfortunately, devastating consequences. So, people may be familiar with President Franklin Delano Roosevelt or FDR, as many New Yorkers will be more familiar with. So, he was actually infected with polio in his 30s and unfortunately left him paralyzed and confined to a wheelchair for the rest of his life.

But as a pediatrician, specifically, the thing that kind of is seared in my brain when I think about polio was actually when I was in medical school, one of our lectures on vaccines kind of showed images of rows and rows of children in these machines called iron lungs. And as I mentioned, polio can infect various cells and cause things like paralysis, and that can include paralysis of the muscles that help you breathe, which is why these machines were developed and needed in the first place. And unfortunately, many of those children were confined to these iron lungs for life and often died very early as a result of it.

That being said though, the polio vaccine development, which is a kind of story in and of itself, led to frankly miraculous results. So, it was developed in the 1950s. And by the late 1970s, polio was eradicated from the United States completely. And so, it really is one of the great vaccine success stories.

Melanie Cole, MS: Well, it certainly is and I thank you for sharing all of that. That was a great answer, Dr. Cullen. And polio was a perfect example that you gave us. Now, the percentage of children receiving recommended vaccinations, we've seen it decline. And if I was to ask you in your opinion and your theories, what are some of the reasons that you see for vaccine hesitancy? Are you seeing some of those diseases coming back? I know my own personal pediatrician for my kids, when measles was coming back, she was literally furious. But I'm wondering what you think as some of the reasons for this?

Dr Sean Cullen: Yeah. It's a really great and important question. And I think that I'll start off by saying that there's a lot of kind of contributing factors to the rise in vaccine hesitancy. I think partially a major contributing factor is actually a function of the success of vaccine development. So, right now, there are upwards of 20 vaccine-preventable diseases that the standard CDC, or Center for Disease Control, recommends as part of the standard childhood immunization schedule. So, that means that there are 20 diseases that children are not getting at the rates that they previously may have before the development of vaccines, and thus parents are not having to take care of infants with those illnesses and not having some of the potentially devastating consequences of those infections.

So, as you can imagine, thinking back to the polio vaccine example, there aren't children's hospitals filled with young children with polio infections. These kids are not in iron lungs, and people are thus not talking about how can we prevent more and more children from getting polio. I'll say for myself specifically, I have never taken care of a child with polio in my 10 plus years of training and time as a pediatrician, which is a great thing. But I can then understand how some parents might process this and think, "Well, I've never even heard of a child getting polio or getting tetanus or getting the measles. So, why do I need to give my child a shot to prevent something that I've never even heard of?" And so, I think results like this, along with frankly those who, in my opinion, peddle and miss and disinformation around vaccines, that's what unfortunately has led to a return of outbreaks of diseases that we have very effective vaccines for. And frankly, it kind of breaks my heart thinking of any child having to suffer as a result of this.

In fact, I actually looked this morning on the CDC's website. And just in 2024 alone, there have been seven outbreaks of measles already in the United States this year. That's from places as far reaching in terms of the country from Florida to Arizona to Michigan and even here in New York. This is very scary to me as a pediatrician, because measles specifically is a highly, highly contagious virus. It can spread through an unvaccinated community like wildfire and we don't typically vaccinate children with the vaccine that protects against measles until they're one year of age. And I mention that because one of the complications, albeit a rare complication, of a measles infection is something called encephalitis, which is basically swelling or inflammation of the brain. And this rare complication can sometimes lead to death, which is obviously a very scary prospect for anyone to think of, parents, pediatricians included.

Melanie Cole, MS: Dr. Cullen, you know, I agree with you. I think that not only have people not heard of it, but there's the myth that, "Oh, well, since it's not prevalent anymore, then I don't have to worry about it." And then as you pointed out, there's a lot of disinformation out there. And it's really running rampant on social media, and that is a shame. And that's why you and I are here today, to clear a lot of that up, because that disinformation is really harming our community. So, speak about the safety and efficacy of vaccines, how they're tested. Because you and I are talking today, and we're specifically concentrating on the vulnerable babies and children, safety is a big issue for parents. It's a big issue. They want to know if this is going to cause too many side effects, how the vaccines are made. Give us a brief answer on the safety of them and how we know as parents.

Dr Sean Cullen: You're 100% right. I think it is imperative for pediatricians, really any healthcare provider, to be a conduit for parents to get their concerns addressed and to answer some of those questions. So in a very brief way, talking about the vaccine approval process, there's an extensive amount of research and clinical trials performed before there's ever any vaccine that's kind of made available to the general public.

The purpose of these clinical trials is to prove empirically with data that a vaccine is both, as you mentioned, safe and efficacious, or basically that it works to prevent or minimize the disease that it's trying to target. So, this happens in a very stepwise fashion with more and more participants in these clinical trials with each step. So first, they want to make sure that the vaccine itself and all of the components included in the vaccine are safe and well tolerated when administered. And then, there are tests that kind of find the appropriate dosage to make sure that the vaccine response, so those antibodies are produced in sufficient amounts to kind of ultimately protect the child. And then, there are even larger tests to basically test the If the vaccine does what it's intended to do, so specifically to prevent the illness itself or reduce the severity of some of those severe signs of infection. So, this is things for like a respiratory virus, for example, that prevent needs for hospitalization or the need for a breathing tube.

And finally, even after they're approved for use, there are these even larger monitoring trials that make sure that there are no long-term side effects from vaccine administration and any really rare side effects that would only appear from testing a large amount of numbers. And then for vaccines specifically, there's this added layer of monitoring for these rare side effects. It's called VAERS, so the Vaccine Adverse Event Reporting System, where anyone can report what they feel may have been a side effect from any vaccine. And these are kind of collected and collated and monitored by the various health agencies in the government. So, there is a lot of testing and monitoring done to ensure that vaccines are safe and effective.

Melanie Cole, MS: Well, thank you. And let's clear this up right now, Dr. Cullen. The link between vaccines and autism is still out there being told around and misinformation, as you and I were mentioning. Clear that up for us right now because as we talk about vulnerable children, vulnerable babies, this is one of the things that parents cite.

Dr Sean Cullen: Absolutely. So, I can say very conclusively that this has been one of the most examined questions in modern pediatric research and that there is no evidence at all for a causal link between routine childhood vaccine administration and autism spectrum disorders. So, that initial paper that came out and reported those findings was absolutely formerly retracted in 2010, and there have been large epidemiological studies, which are basically just a fancy way of saying looking at the rates of various diseases that have found no linkage between vaccination and autism spectrum disorder.

But for interested parents, a book I'll often recommend is one by Dr. Peter Hotez called Vaccines Did Not Cause Rachel's Autism, My Journey as a Vaccine Scientist, Pediatrician, and Autism Dad. And I can say Dr. Hotez is an MD, PhD, and a pediatrician like myself. And he actually currently works where I trained, did my MD PhD training, at Baylor College of Medicine in Houston, Texas. And he is a world-renowned vaccine scientist whose life's work has actually been to develop vaccines for COVID-19 for neglected tropical diseases. So, those are ones that typically affect those in developing countries with the lowest socioeconomic status. And he also happens to have a now adult daughter with autism. And he breaks down in the book, in very easy to understand language, all of the evidence about why autism and other neurodevelopmental disorders are likely the result of both a genetic disorder, and one that begins even prior to birth, and also breaks down all of the myths and disinformation regarding that concern for a link between vaccines and autism.

Melanie Cole, MS: Very clear. And I'm so glad that you made that very clear for parents listening. Now, as we're talking about vulnerable babies and children, what is the best way, Dr. Cullen, to protect children that are too young? As you mentioned, the measles vaccine can't be given until a year or too vulnerable. For some reason, they can't get the flu shots. They can't get their MMR for some reason. Tell us a little bit about what vaccines are most common for vulnerable populations and children. Tell us a little bit about what those vaccines are and what do we do about it.

Dr Sean Cullen: This is a great question that I often will hear being asked of myself, both in my personal life, as my friends and family who know I'm a pediatrician will kind of reach out about, but also in my professional life as well. And one of the things I say to protect our most vulnerable children, both the very young and those who have underlying medical conditions that make them more prone to the severe side effects of some of these vaccine-preventable illnesses that we've been discussing.

The best way to kind of help protect those people is to make sure that those in closest contact with them who can be vaccinated are all fully vaccinated themselves. There's this concept in vaccine science, it's called herd immunity. It's basically the idea that a disease cannot easily spread through a community if there are few to no available hosts or people that the bacteria or virus can infect and then go on to infect others. So, a great example of this is the MMR vaccine, which is a vaccine that actually protects an individual against three different viruses, so measles, mumps, and rubella. And the way that this particular vaccine works is that it contains live, very weakened forms of the viruses. So essentially, it's able to not effectively replicate like the actual measles, mumps, and rubella viruses, so you don't get sick with those viruses, but there's enough to inform your immune system of what the real viruses "look like" and develop those protective antibodies we mentioned to help basically establish lifelong protection from infection.

And so as far as kind of what I do personally to improve vaccination rates, is really listen to parents. I think it is imperative that healthcare providers address these real concerns that families have. But I will say I always start off the conversation by saying up front I'm a pediatrician, a neonatologist, and a scientist and I highly recommend that families vaccinate their children with all recommended vaccines at the appropriate ages.

But then, I next ask them to tell me what questions or concerns they have. And then hopefully, by listening first and then answering, I can allay any concerns or fears they may have. In my experience, and I think it goes without saying for anybody listening, that parents just want to do what's best for their children. And it's our job as pediatricians to help them reach that goal with the support and assurance of our own expertise.

Melanie Cole, MS: Dr. Cullen, this has been such an enlightening episode and an enlightening interview and discussion. And I understand that you have a personal connection after losing your brother to RSV. Can you please tell us a little bit about that, if you would, and how it's impacted your personal passion and interest in this topic?

Dr Sean Cullen: Thank you so much for asking. So yes, my younger brother, Kevin Patrick, he was born almost 30 years ago. And when he was born, he had a pretty severe congenital heart defect, which is called transposition of the great arteries, which basically means that the big blood vessels that come off the heart developed incorrectly. And it left him with the inability to pump oxygenated blood to the rest of his body effectively. So because his heart defect was not known before he was born, he had to be urgently transferred from a community hospital to a NICU here in New York City. He was thankfully stabilized and able to come home to us, and was due to have a number of operations to kind of correct this heart defect. But unfortunately, when he was about 10 months old, he died due to complications from an infection from RSV.

And RSV is a kind of virus, it's called respiratory syncytial virus, and these infections are extremely common among children. I'm sure many of the parents listening have had experience with their children being infected with RSV at some point in their life. But it can be extremely dangerous for medical complex children like Kevin. And I'm just really happy to report that as of the end of 2023, there are two new tools to protect children like my brother and others from the effects of this virus. So, there's a vaccine called Abrysvo that can actually be given to pregnant women that will produce those antibodies we've talked about against RSV, which are then able to cross the placenta, which is something that happens for a lot of antibodies and is how early babies, those very vulnerable infants, it's kind of a natural mechanism that exists for protection from various bacterial and viral infections. And those antibodies crossing the placenta and entering the infant actually protect that infant for the first six to nine months of their lives.

There's also a specially formulated antibody against RSV called Beyfortus that can be given after birth to the baby to provide the same protections. And it's also recommended for high-risk children like my brother to be given during their second RSV season to make sure they have even more lasting protections. Both of these tools have been shown to be really great at reducing severe infections like pneumonia in young infants, which can often lead to hospitalizations and even the need for a breathing tube in an intensive care unit. And my family and I, I'll say just speaking personally, are so grateful for the advancement of science in such a relatively short time frame that there's hope that no other families will have to experience the kind of loss that we endured with the aid of what I consider to be one of the miracles of modern science, which is vaccines.

Melanie Cole, MS: Beautifully said, and thank you for sharing your story, Dr. Cullen. And for parents and caregivers listening, if you have any questions, please speak with your pediatrician. It's so important that we clear up a lot of that misinformation out there. Vaccines have really been the miracle medicine of the century, as Dr. Cullen so beautifully said. So really talk to your pediatricians if you have any questions. And Weill Cornell Medicine continues to see our patients in person as well as through video visits and you can be confident of the safety of your appointments at Weill Cornell Medicine. That concludes today's episode of Kids Health Cast.

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