toddler sits on exam bed in clinic playing with toys and books before vaccine appointment

Preventable illness and death alter and claim millions of lives every year, and medical professionals recommend vaccines to help prevent these tragedies.

However, the number of vaccines recommended by the Centers for Disease Control (CDC) can be overwhelming and even frustrating, especially for caretakers who may question the need for so many shots. Alexandra Clark, MD, division chief of general pediatrics at Loma Linda University Children’s Health, breaks down why vaccines play an important role in protecting children and how immunization needs change as they grow.

Why are vaccines important?

Immunization is all about preventing vaccine-preventable infections and deaths. But it’s also about preventing the circumstances that result from a child’s illness, such as missed time from work or school, financial challenges, the emotional and physiological stress for both the child and caretaker, and, in tragic circumstances, lifelong complications such as chronic illness. No parent wishes these circumstances upon themselves, but misinformation can cause well-meaning caretakers to make choices that negatively impact their lives forever.

“We fully recognize that every parent is going in with the idea of how to make the best decision for the wellness of their child,” Clark says. “We want parents to know what the evidence supports to ensure that we’re not leaving their child unprotected against a preventable disease that severely impacts children today.”

Some of the most common immunizations include hepatitis A, hepatitis B, rotavirus, polio, chicken pox, influenza, measles, and tetanus.

Why so many vaccines at different times?

When a child is born, they have an immature immune system. Some of the mothers’ immunities pass to the child through the placenta, and breastfeeding supports this immunity, but Clark says a mom’s protection doesn’t last forever. After birth, the immunity the baby received from its mother begins to fade, and vaccines can bolster the baby’s immune system to replace this support

Here's how it works: vaccines introduce a protein, antigen, or other material into the immune system to trick the immune system into thinking that it has been exposed to a particular deadly disease without actually being exposed. This triggers the immune cells into creating their own immunity, and a series of vaccines delivered at different stages of growth help to build up the immunity over time. The repeated exposure to the vaccine ensures the child reaches a safe level where they are fully protected. This explains why the same vaccines are given at different months and years of life — a little bit given several times will not overwhelm the immune system and will instead carefully build the system’s immunity to that disease. As the immune system ages, it can give a more robust response to a single vaccine, so vaccine series become less necessary. Clark says immunization needs wane but continue to follow us through adolescence and into adulthood.

Clark says researchers in vaccine clinical trials examine the dose of the vaccine that creates the appropriate response, the safety of that dose, and the side effects. Children’s vaccines are tested in older consenting adults before they are adjusted and used for younger people.

“It’s heartbreaking to lose an infant to a virus that there’s a vaccine for,” Clark says. “The heartbreak for that family is forever. It is not something that will be easily overcome.”

Why so many different vaccines?

Clark says that risk of exposure is a key detail in vaccine science. Vaccine researchers find the ideal intersection between exposure risk and vaccine potency to combat illness and to ensure children are safely protected before they are likely to be exposed to illnesses. Therefore, the vaccines chosen for each stage of a child’s life are based on the amount of risk to that child. For babies, vaccines are chosen that will combat common diseases that cause infant mortality, lifelong morbidity, or severe mental challenges. These are all diseases they are likely to be exposed to as infants. As children grow, the immunizations recommended for each age are based on the illnesses that will pose a threat to the child as they reach that age.

Clark says while it would be wonderful if vaccinations were able to eradicate disease entirely, very few diseases have been entirely eradicated. There is risk that a vulnerable population will contract one of these diseases and be severely affected.

Most recently, the coronavirus pandemic has taken a major toll on families across the world. According to the CDC, COVID-19 is one of the top 10 causes of death in children ages 5 through 11 years. Since this disease can cause severe illness, death, and both short- and long-term health complications, safe vaccination is a top priority for healthcare workers. Clark recognizes the risk of vaccinating but reminds parents of the tremendous risk of their children contracting COVID-19.

“The risk of the infection is quite significant,” Clark says. “Our hospitals and emergency departments are not flooded with children or adults coming because of extreme side effects from the vaccine. We are having our hospitals flooded with families who are impacted by live coronavirus and who are often unvaccinated.”

Clark reminds caretakers to be careful of their information sources, especially when it comes to vaccines.

To learn more about immunizations, talk to your doctor or schedule an appointment online.