Why do children receive vaccines on a schedule? What happens in the body when a child is vaccinated? And when communities see declining vaccine rates, who faces the greatest risk?
Storm Dorrough, MD, a pediatric infectious disease fellow at the Medical College of Wisconsin, joined Coffee Conversations with Scientists to break down the evidence and address what families are genuinely asking.
Key Takeaways
Vaccination works by preparing the body. When a child receives a vaccine, a component of a virus or bacteria is introduced into the body, giving the immune system a chance to recognize it and learn to fight it without the person getting sick. If that infection appears later in life, the body is ready.
Mild symptoms after a shot, such as a sore arm, low-grade fever, or a day of feeling off, reflect that immune response. That response is the immune system engaging, not the infection spreading.
This distinction matters because it gets at one of the questions parents frequently wonder about. The flu shot trains the body to respond to the flu, not to get it.
Decades of research inform the childhood vaccine schedule, which is built around two realities: young children are especially vulnerable to serious illness, and there is no reliable way to predict when a child will be exposed to any given infection.
Some respiratory infections pose little serious threat to adults but can cause life-threatening illness in infants. Consider hepatitis B: There is no reliable way to predict when a child might be exposed, so vaccinating early ensures protection is already established across those years.
The number of doses matters, too. Multiple doses in early childhood are what the evidence shows are needed to produce a strong, lasting immune response. The schedule reflects decades of research on what works.
Vaccine recommendations do evolve, and for families already navigating a crowded information landscape, that can feel unsettling. Updates to vaccine guidance reflect ongoing surveillance and new data, not instability in the underlying science.
As Dr. Dorrough noted, "We are constantly analyzing and reviewing to make sure we're providing the best possible strategy to prevent serious illness in people with the least amount of serious side effects."
Rotavirus is a useful example. An earlier formulation was linked to a serious side effect and was pulled from the market until a safer version was available. That response reflects how the system is designed to work: monitoring outcomes, identifying problems, and adjusting course.
Measles was effectively eliminated in the United States through decades of sustained vaccination. Its return in communities across the country is a direct consequence of declining vaccine uptake and a concrete illustration of how community immunity works and what happens when it breaks down.
Preventing measles from spreading requires roughly 95% of a population to be vaccinated. When that threshold drops, the virus finds room to move. The communities hit hardest by recent outbreaks have been those with lower coverage rates, often driven by misinformation or religious exemption.
The people most affected by those gaps are often those who cannot be vaccinated themselves. Children with cancer, infants too young to be vaccinated, and people with compromised immune systems cannot protect themselves through their own vaccination status. They rely on the people around them. As Dr. Dorrough put it, "By uptaking and buying into this system, we're helping protect all of these people around us who we don't always [recognize as vulnerable]."
Vaccine confidence is strained in some communities, but the picture is not uniformly discouraging. Families across Wisconsin are asking more questions than ever, and that curiosity, met with honest and patient conversation, is an opening rather than an obstacle. Healthcare providers are working harder to meet families in the middle, addressing misinformation with evidence and empathy rather than authority alone.
If you have questions about your child's vaccines, bring them to your pediatrician or family medicine provider. And if your hesitation is rooted in past harm or distrust, finding a provider who will take the time to hear that can make a real difference.
To learn more about the science behind pediatric vaccines, watch the full Coffee Conversations with Scientists episode featuring Dr. Dorrough.