Ashlee Williams, MD (Host): When it comes to childhood vaccinations, parents are met with a flood of information; some helpful, some confusing, and some simply untrue. Social media headlines and well-meaning conversations can blur the lines between fact and fiction, making it hard to know what to trust.

Welcome to The Healthier You Podcast. I'm Dr. Ashlee Williams. And today, I'm joined by Dr. Takeema Dixon, a board-certified pediatrician here at Kaiser Permanente. In this episode, we're going to take a clear evidence-based look at common vaccine myths and the facts behind them so parents can feel confident about the decisions that they're making for their children's health.

 We'll break down how vaccines work and the actual science behind it without judgment and without jargon. Thank you so much, Dr. Dixon, for joining us for this important, timely conversation today.

Tekeema Dixon, MD: Yes. Thank you so much, Dr. Williams, for having me as a pediatrician. This topic means a lot to me.

Host: It's so much in the news right now. All right. So, how can parents know that the information that they're hearing about vaccines is trustworthy?

Tekeema Dixon, MD: That's a really good question and a really big task for parents. Right now, as you mentioned, parents are getting information from so many different sources. It's important for parents to first remember that social media and the personal stories that are often embedded in posts really serve to amplify fear sometimes without context or scientific accuracy. So, the most reliable source is always going to be a family's pediatrician or family medicine doctors and other healthcare providers.

I'd also like to comment a little bit about the vaccine schedule. For decades, our country's immunization recommendations were informed through a really thoughtful, incredible process where, each year, a group of pediatric health experts get together, review all the current research and update immunization recommendations if needed. So, providers now and then are going to continue to make recommendations based on trusted sources like the American Academy of Pediatrics and their evidence-based vaccination schedule.

And we have the shared goal of keeping children and our community safe and healthy. So, American Academy of Pediatric Resources, like the healthychildrens.org website is a reliable place for parents to go to get good information. So, I recommend that. And I always recommend that parents take the questions that you have and bring them to us as your trusted providers so that we can help you because we care deeply about your child's health.

Host: I think one of the biggest questions out there right now are why are these vaccines recommended so early in childhood?

Tekeema Dixon, MD: Which is a fair question. You know, the vaccine schedule is designed again by pediatric health researchers who have dedicated their lives to the work. And it's not randomly designed, but the pacing and the timing of the schedule is really important. So, the goal of the schedule is to protect infants and children based on two things. First, based on when the vaccine will work best with the child's immune system. And second, to really help an infant's body to recognize and to resist germs when a child is at the highest risk for getting really sick from these illnesses. So, there are germs that may not be harmful to adults, but in a baby can make them really sick. And exposure to illnesses like the flu or pertussis or measles when a child's immune system is developing are just more dangerous and they're at higher risk for severe lung infections that can require hospital stays and have serious complications. An early start with immunizations really helps the body's immune system to learn and to grow as infants and children are growing.

Host: I think most people will agree that there are a lot of vaccinations that are recommended for children. I have two young kids myself. When I take them to the doctor, it always feels like they're at least getting two to three vaccines, especially when they were much younger. Is it possible that too many vaccines can overload the immune system of a child?

Tekeema Dixon, MD: Well, the interesting thing is that a child's immune system is constantly learning to read germs. We are both parents and, as many parents know, kids love germs and they're really good at finding germs with no help from us as parents. So to just slip in one medical term, when germs are exposed to the immune system, we call them antigens.

 So, an interesting fact is that a child's immune system is exposed to over 1000 antigens per day, and this is just while they're interacting with pets or touching surfaces or toys and just playing. So as a contrast, vaccines contain only a tiny fraction of the antigens that the immune system is exposed to on a daily basis. And vaccines introduce these antigens in a very targeted way so that we're giving the immune system helpful practice at recognizing these specific illnesses.

Adhering to the vaccine schedule, if families stay on schedule, we protect children against 20 preventable illnesses that can have potentially severe complications. So, the vaccine schedule, it's safe, it's intentional, and it's important to remember that the body sees germs in larger volumes on a regular basis.

Host: And peaking of the vaccine schedule, it's not like every time you come to the doctor, you're getting a brand new vaccine every time. Some of these vaccines need multiple doses or booster. Can you talk about why that's necessary?

Tekeema Dixon, MD: Yeah, that's a really important point. So, some vaccines require multiple doses because the immune system learns in stages. So once babies are born, their immune systems are ready to learn, but this takes time. Vaccines are allies that really guide the immune system on that journey. So, the first dose introduces the immune system to that antigen or germ. The first step is to prepare the body to recognize and resist disease.

Subsequent doses help to create long-term memory cells that store the instructions so that the body can identify germs for a longer time. So, you can think of it like building muscle. It takes repetition to create long lasting strength and booster doses help to maintain long lasting immunity. So, this is especially for diseases that sometimes the protection from these illnesses weigh in with time, like the flu, it's the reason that we have to get a flu vaccine every season. So, this approach ensures long lasting protection during the years when children are most vulnerable.

Host: All right. Dr. Dixon, I'm going to throw out another hot question for you. Are vaccines linked to autism or developmental delays?

Tekeema Dixon, MD: This has been one of the most thoroughly studied questions in modern medicine. There have been large scale studies involving millions of children across multiple countries that have consistently found no link between vaccines and autism or developmental delays. The origin of this claim came from a very small study that was published in the 1990s that was later proven to be fraudulent and was formally retracted.

That said, I do wantt to acknowledge that we do see autism more commonly now, and there are many reasons for this. We know now that there are over 100 genes associated with autism. And over the years, we've developed better screening tools in a more standardized approach to screening. So while we are seeing more autism, we also have decades of science from across the globe that confirms that vaccines do not cause autism or developmental delays.

Host: Okay. But we do know there are some side effects to vaccinations. Can you talk about some of the common side effects that you see in your clinic with vaccines?

Tekeema Dixon, MD: Yes, and there certainly are. However, most vaccine side effects, they're mild and short-lived, so you can have soreness or redness or swelling at the injection site most commonly. However, you can also have symptoms like fatigue or body aches or low-grade fevers. Although it's important for families to know that these are actually signs that the immune system is working and responding as intended.

Serious adverse reactions to vaccines are extremely rare, and I'll even say that they're far more rare than the complications that are caused by the diseases that vaccines prevent. So from a risk perspective, choosing not to vaccinate carries a much higher risk or likelihood of serious harm than vaccinating from that perspective.

Host: We also know that vaccines aren't completely pure. They're mixed with some ingredients. Are those ingredients within the vaccine safe?

Tekeema Dixon, MD: This is a really common question and it makes sense for families to have some concerns about ingredients. The key thing to know is that every ingredient in a vaccine is there for a reason, and it's used in very small, carefully studied amounts.

So, I want to talk about two that come up commonly. So, aluminum first, aluminum is a salt. It's one of the most abundant salts that's found in soil. We do add a small amount of aluminum to vaccines. The reason is because it helps to create a stronger immune response. It makes the vaccine more effective so that we get better response using less vaccine and fewer doses. And it's also important to know about aluminum, babies are actually exposed to more aluminum on an everyday basis than what is in vaccines. So to give you more specifics, pediatric health experts have found that infants and children ingest about seven to nine milligrams of aluminum per day. And you can think of one milligram as being like a grain of sand. So, we're talking the equivalent to seven to nine grains of sand a day. And this is just from infants drinking breast milk, formula, food, or even water. So compare that to the amount in vaccines, which is just a small fraction of this, like less than a half a milligram. So, the equivalent of the less than a grain of sand in some vaccines. So, aluminum toxicity is not something that you see from the small amount that's in vaccines. It just gets excreted out in urine.

And I'll also say that there have been large studies of over millions of children, a recent study of over a million children that came out in Denmark specifically, that showed no association between the aluminum in vaccines and any health condition. And then, they looked at a lot of them, including asthma, allergies, autoimmune disorders, and neurodevelopmental conditions.

The other vaccine ingredient that comes up a lot is a preservative in vaccines that's called thimerosal.. Thimerosal contains a form of mercury called ethylmercury. And this is different than the mercury that we worry about in certain fish. Ethylmercury doesn't build up in the body. It clears quickly. Even so, it's been removed from almost all routine childhood vaccines in the US, except for some multi-doses of flu shots. And that removal was just made out of an abundance of caution and not due to any safety concerns. So again, there have been large studies over the years that show no connection between any vaccine ingredients and developmental problems.

Host: So if a disease like polio is rare today, is that vaccination still necessary?

Tekeema Dixon, MD: Yes. So, diseases are rare precisely because vaccines have been one of the most successful medical advances of our time. So when children receive all of the recommended vaccines on time, our whole community benefits. High immunization rates help to create community immunity, which means widespread protection against contagious diseases. When vaccination rates decline, however, that's when outbreaks happen. And we've seen this happen recently with measles and even with whooping cough in recent years.

Many of these illnesses, it's important to remember also are still circulating globally, and they could be reintroduced through travel. So, stopping vaccinations because a disease is rare would be the equivalent to stopping seatbelt use because accidents are less common. And it's important to remember that when children receive the recommended vaccinations on time, it stops preventable diseases from spreading through our communities.

Host: Thanks on touching on why it's important for communities to vaccinate. Can you talk a little bit more about why it's important for communities to vaccinate and not just individuals?

Tekeema Dixon, MD: Yeah. So, it's important to keep in mind that there are some children, such as newborns or children undergoing cancer treatment, or those with immune disorders that can't be vaccinated, and they really rely on others for protection. And the same goes for older adults. So when enough people are vaccinated, diseases have fewer opportunities to spread. And we call this again community immunity. When everyone adheres to the recommended schedule, the community immunity prevents outbreaks so that even the most vulnerable members of our community have an opportunity to stay healthy. And this is really important.

Host: Can natural immunity replace vaccines?

Tekeema Dixon, MD: Natural infection can certainly lead to some immunity, but it's important to remember that this comes at a cost. Natural immunity means that a child has to first get sick, which can potentially lead to hospitalizations and long-term complications or even death. In recent flu years, we keep breaking records in a really bad way. Last year, we had a record high number of pediatric deaths. And it's important to know that 40% of these were in children that had no high-risk conditions, and most of these children were unfortunately unvaccinated. Vaccines provide immunity without exposing children to such dangers. So, it's a far better option with much less risk.

Host: Thanks for the insight Dr. Dixon. Here are five takeaways from today's episode. Vaccines are carefully timed to protect children when they're most vulnerable. The recommended schedule is based on decades of research and is designed to prevent serious illness before children are exposed. Vaccinations contain fewer antigens than what children encounter every day, and they help train the immune system safely and effectively.

Claims linking vaccines to autism or developmental harm are not supported by science, while vaccines themselves are extremely closely monitored. Vaccine ingredients are safe and used in very small amounts. Ingredients and vaccines are well-studied and present at levels well below what children encounter in everyday life.

High vaccination rates help prevent dangerous outbreaks and protect those who can't be vaccinated, making vaccines critical for both individuals and the community.

For more information from our experts, visit kp.org/doctor or listen to Healthier You wherever you get your podcast. If you found this episode helpful, please be sure to share it with others. Have questions or health topics you'd like for us to address in future episodes? Let us know in the comments. Thank you. And from all of us at Kaiser Permanente, be well.