Maggie McKay (Host): Welcome to Conversations Like No Other, presented by Valley Health System in Paramus, New Jersey. Our podcast goes beyond broad everyday health topics to discuss very real and very specific subjects impacting men, women, and children. We think you'll enjoy our fresh take. Thanks for listening. I'm your host, Maggie McKay.

Today, we have with us Dr. Christiana Farkouh, Associate Director of Neonatology and Director of Pediatrics, and Dr. Falguni Shah, Pediatric Infectious Diseases Consultant at Valley Hospital, to discuss understanding childhood vaccines. Thank you both for being here today.

Dr. Christiana Farkouh-Karoleski: Thank you for having me.

Dr. Falguni Shah: Thank you for having us.

Host: So, what is the current childhood vaccine schedule, and who develops it, and which serious diseases does it protect children from?

Dr. Christiana Farkouh-Karoleski: So here in the United States, the routine childhood immunization schedule is developed by our Centers for Disease Control, specifically its advisory committee on immunization practices, together with groups like the American Academy of Pediatrics and the American Academy of Family Physicians. Our vaccine schedule protects against many diseases and includes diseases like measles and mumps, rubella, diphtheria, tetanus, pertussis, which is also known as whooping cough, Haemophilus influenzae type B, and many other illnesses.

And the schedule actually probably has its initial origins as far back as 1995 when these groups came together to harmonize the schedule. But it is reviewed annually, and adjustments are made based on new evidence from clinical trials or safety monitoring data, also based on disease prevalence and changes that may happen there.

Host: How effective are routine childhood vaccines overall?

Dr. Falguni Shah: So overall, routine childhood vaccinations are among the most effective public health interventions ever developed. And most vaccines on the schedule demonstrate an effectiveness anywhere between 85% to well over 95%, of course, depending on the disease, the vaccine platform, and the outcome being measured.

The impact of childhood vaccinations is best appreciated at a population level. So since the introduction of routine vaccination programs, we've seen reductions of greater than 90% in diseases like measles, polio, diphtheria, and invasive Haemophilus influenzae type B disease. In some cases, the disease that once caused thousands of deaths and hospitalizations annually have become exceedingly rare.

So, it is important to understand that vaccine effectiveness can be measured in many different ways. Some vaccines are extraordinarily effective at preventing infections altogether. For example, two doses of the MMR vaccine are about 97% effective at preventing measles. Other vaccines may not completely prevent infection in every individual, but they are highly effective at preventing severe disease or hospitalization or long-term complications.

Host: Why do some vaccines like those for influenza appear less effective than others?

Dr. Falguni Shah: So, influenza viruses evolve very rapidly through a process called antigenic drift, and scientists have to predict which strains will circulate months in advance, and sometimes the match is not perfect. As the virus changes, the immunity from previous vaccinations may become less protective. Now, in contrast to these, viruses such as measles are genetically stable, allowing the vaccines to maintain a very high effectiveness over decades.

Host: In real-world practice, do vaccinated children still get these illnesses? And if so, how does the illness differ?

Dr. Christiana Farkouh-Karoleski: So yes, vaccinated children can still get the illness. However, and this is a big but, illnesses are usually much milder, and they have a lower risk of complications, hospitalizations, and even death.

Host: How are vaccines developed and what are the different types?

Dr. Falguni Shah: So, vaccines may contain different parts of the microorganisms. They may contain weakened organisms, inactivated organisms, sometimes purified proteins, polysaccharides, viral vectors, or even some genetic instructions like mRNAs. And each platform trains the immune system to recognize the pathogen before the natural infection occurs. So, it stimulates the immune system differently. The selection of what to use from the microorganism to develop the vaccine depends on the characteristics of the pathogen and the type of the immune response needed for protection.

Host: Are some platforms more effective or safer than others?

Dr. Falguni Shah: So, no single platform is ideal for every disease. Some pathogens require strong antibody responses and others require cellular immunity. So, it's a difference in the type of immunity that needs to be generated. Scientists choose the platform that provides the best balance of safety, durability, manufacturability, and the effectiveness. And vaccine development is then tailored to the biology of each infectious agent.

Host: How is vaccine safety monitored both before and after approval? And are there systems in place to detect rare side effects?

Dr. Falguni Shah: For sure. So before approval, the vaccines undergo lab testing, animal studies, and multiple phases of human clinical trials involving thousands to tens of thousands of participants. And after approval, those safety monitoring continues through large surveillance systems that can detect the rare adverse events not identifiable during these clinical trials.

Host: And why might vaccine recommendations differ between countries?

Dr. Christiana Farkouh-Karoleski: Differences depend on several reasons and can include the disease prevalence in a particular region or part of the world. Like for example, in Brazil, routine immunization against yellow fever is routine. But not here in the United States or in Europe because yellow fever is not a disease that is prevalent in these areas.

Other factors that really impact why vaccine schedules can differ are things like access to healthcare. And if healthcare is a universal healthcare system or a more fragmented healthcare system. Cost and access can factor as well as just public health priorities that may differ from one country to another and one part of the world to another.

Host: What are the real benefits of vaccinating children, not just individually, but for families and communities?

Dr. Christiana Farkouh-Karoleski: So, the first benefit is to the child him or herself, and the vaccine protects that child from serious illness. It also prevents against outbreaks in the community. And by preventing these outbreaks in the community, ultimately protects vulnerable people who either can't be immunized or are immunocompromised.

This broader type of protection is also known as population immunity, or sometimes you also hear it called herd immunity. And that refers to what happens when a large portion of the community becomes immune, usually through vaccination, to a specific disease, making person-to-person spread of that disease very unlikely. And a result of this herd immunity or population immunity is that even those who are not immune are now protected.

Host: And what are the known side effects and how common are they in day-to-day practice?

Dr. Christiana Farkouh-Karoleski: So, most side effects are mild and can include things like soreness, fever, fatigue. Rarely are there complications or side effects like severe allergic reactions. These are estimated to be about one in a million.

Host: How do those risks compare quantitatively to the risks of the diseases themselves?

Dr. Falguni Shah: So for most vaccine-preventable diseases, the risk from the disease is far greater than the risk from the vaccines. The risk of serious vaccine-related adverse events is generally measured in a few cases per millions of doses. In contrast, vaccine-preventable diseases historically have caused substantial hospitalization, disability, and mortality rates.

So, the difference in magnitude between vaccine risk and disease risk is often several orders of magnitude, and vaccinations are recommended because the benefits of preventing the disease overwhelmingly outweighs the known risks of vaccinations.

Host: And you know, many parents worry about links between vaccines and conditions like developmental delays or autoimmune diseases. Where do these concerns come from?

Dr. Falguni Shah: So, many concerns arise because vaccines are administered during the same developmental period when certain medical conditions first become apparent. So, the timing can make it seem like the two are related. But temporal association, of course, does not establish causation, right? So, large epidemiological studies involving hundreds of thousands of children have consistently found no evidence that routine childhood vaccinations cause developmental delays, autism, or any other neurological disorders.

Host: Why has the MMR vaccine become such a focus of concern, and where did the idea of a link to autism originate?

Dr. Falguni Shah: So, the concern originated from a small study that was published in 1998 that suggested a possible association between the MMR vaccination and autism. But the study was subsequently found to contain very serious methodological and ethical problems and was actually formally retracted. And extensive research involving millions of children worldwide has been subsequently done, and there's no evidence found that vaccines cause any autism or developmental delays. Multiple large cohort and case control studies have been done. They've been conducted in several countries, and no association has been found. So, the scientific consensus is based not on a single study, but worldwide multiple studies.

Host: How should parents interpret this evidence today?

Dr. Falguni Shah: So, the scientific consensus is based on worldwide studies and parents should recognize that the question has been extensively studied and consistently answered that there is no evidence of linkage between vaccinations and autism or developmental delays.

Host: Some parents feel it's more "natural" for children to get infections and build immunity. How do you approach that conversation?

Dr. Christiana Farkouh-Karoleski: It's true that natural infection can provide immunity, but this comes at a cost, and it's important to appreciate that. Risk of severe illness, complications, and death are that cost. Some diseases can cause permanent damage, brain injury, and swelling. For example, measles is known to do that.

Host: What are the real risks of relying on natural infection?

Dr. Christiana Farkouh-Karoleski: So, the real risks come from what happens if the child does contract the disease and has complications from that. So for example, diseases like measles can have some real long-term risks associated with brain injury and swelling. Measles in particular has a side effect called amnestic immunity, meaning that after a measles infection, it wipes out the body's immune response to subsequent infections, even infections that that child or individual may have had previously, which then obviously can make that child or individual susceptible to secondary infections and continued complications.

Host: And what are the risks of choosing not to vaccinate at all?

Dr. Falguni Shah: So, I will add on to what Dr. Farkouh delineated at the risk of natural infections. Individuals who remain unvaccinated, of course, are at increased risk of infection, severe disease, hospitalization, and transmission to others. So as vaccination rates decline, outbreaks become more likely, particularly among vulnerable populations.

Host: What happens to herd immunity when vaccination rates decline?

Dr. Falguni Shah: So, herd immunity occurs when enough individuals are immune to interrupt the transmission chains. But highly contagious diseases like measles require very high levels of population immunity. When the vaccination coverage falls below these thresholds, outbreaks can occur. Recent measles outbreaks do illustrate how quickly vaccine-preventable diseases can reemerge when the immunity gaps develop.

Host: And where do parents get reliable information for the vaccines?

Dr. Christiana Farkouh-Karoleski: Well, I'll start by saying that this is such a challenging time with so much conflicting information and, sadly, some of it misinformation. I do want to emphasize that vaccines are one of the most studied and one of the most successful interventions in modern medicine, having saved over 150 million lives globally over the last 50 years and accounts for roughly 40% reduction in infant mortality globally.

Vaccines are so important and reliable resources include organizations like our own Centers for Disease Control, the World Health Organization, the American Academy of Pediatrics. And I'll just emphasize that if anyone does have questions or concerns about vaccines, speak to your healthcare provider, to your child's healthcare provider, and have that honest conversation. We all are advocating for the health and wellbeing of our whole community one person at a time, and vaccines are an important part of that.

Host: Well, thank you both so much for sharing your expertise and time today. It's been so informative. We appreciate it.

Dr. Falguni Shah: Thank you for having us.

Dr. Christiana Farkouh-Karoleski: Thank you.

Host: Absolutely. Again, that's Dr. Shah and Dr. Farkouh. For more information about pediatric care at Valley Health System, please visit valleyhealth.com/childrenshealth. Thanks for listening to Conversations Like No Other, presented by Valley Health System in Paramus, New Jersey. I'm Maggie McKay. For more information on today's topic or to be connected with today's guest, please call 201-447-8388. That's 201-447-8388, or email valleypodcast@valleyhealth.com.