Rethinking Childhood Vaccine Schedules

Childhood immunizations have had an enormous impact when it comes to protecting infants and school-age children from vaccine-preventable diseases. However, a shift in public opinion linked to the anti-vaccine movement has raised questions about vaccine efficacy and safety, particularly among parents of young children. Despite the well-documented health benefits of routine childhood immunization, the past few decades have seen a notable increase in the numbers of parents who request an alternative vaccination schedule that differs from the childhood vaccination schedule recommended by the Centers for Disease Control and Prevention (CDC).¹ 

In a national telephone survey of 1,500 parents of children ages 6 months to 23 months, approximately three percent of respondents had refused all vaccines and 19.4 percent had refused or delayed at least one of the recommended childhood vaccines. Another study conducted in a metropolitan area of Oregon reported rates of alternative immunization schedule usage have increased nearly fourfold in recent years, and in some parts of the country the use of “personal belief exemptions” from vaccinations has grown to rates in excess of five percent of the school-aged population.²

This changing tide of opinions on childhood vaccines often puts pediatricians on the frontlines of educating wary, vaccine-hesitant parents. The American Academy of Pediatrics (AAP) revealed 75 percent of pediatricians it surveyed have encountered vaccine hesitancy. Physicians state the most common parental concerns were the belief that vaccines are unnecessary and the fear that they cause autism.2 Clearly, the increasing frequency of vaccine resistance or even refusal indicates there are significant barriers to overcome to ensure the next generation of children are immunized and protected from vaccine-preventable diseases.  

Understanding Vaccine Hesitancy

The term vaccine hesitancy has emerged in recent years to help depolarize the “pro” versus “anti” vaccination rhetoric that has made a once benign topic so contentious. Vaccine hesitancy is characterized by the World Health Organization (WHO) as “a behavior influenced by a number of factors, including issues of confidence (do not trust a vaccine or a provider), complacency (do not perceive a need for a vaccine or do not value the vaccine) and convenience (access).”³

According to WHO, those who are vaccine-hesitant may display varying degrees of indecision about specific vaccines or about vaccinations in general. In some cases, vaccine-hesitant individuals may accept vaccines overall, but remain concerned about them, or they may refuse or delay some vaccines but accept others. 

WHO acknowledges the reasons people choose to delay or refuse vaccinations are complex. For example, in the United States, vaccine-preventable diseases have been significantly reduced through the use of antibiotics, improved medical technology, better access to healthcare and routine vaccinations, which has resulted in an entire generation who do not perceive vaccine-preventable diseases as a threat.²

One of the biggest drivers of vaccine hesitancy among parents of young children revolves around perceptions of risk. Fears of detrimental side effects are a prime reason parents refuse traditional vaccine schedules. And, although it is more widely publicized now, the misinformation surrounding vaccine risk is not new. In the 1970s, for example, the diphtheria, tetanus and pertussis (DTaP) vaccine was alleged to cause high fevers, seizures and even permanent brain damage, causing some parents to reject the vaccine for their children. Although large epidemiological studies eventually proved the safety of the vaccine, many parents remained fearful and skeptical. Similarly, concerns about the measles, mumps and rubella (MMR) vaccine leading to autism is a narrative that surfaced in the 1990s. Although widely debunked in multiple scientific studies, suspicions and fears linger.³

There are also parents who do not question the safety of a specific vaccine, but rather are wary of multiple vaccines administered simultaneously, either as several shots or as combined vaccines given with one shot. To alleviate concerns, these parents may opt to delay some vaccines in a manner that conflicts with CDC guidelines. “Some parents feel that giving so many antigens in the same visit is not healthy for the child,” says Duke Global Health Institute faculty member Lavanya Vasudevan. “The perception is that we’re overburdening the child’s immune system, but we’re actually constantly exposed to pathogens and antigens that stimulate our immune system in our daily lives.”⁴

In explaining the shift in perspectives on an alternative vaccine schedule, Jeffrey Paul Baker, MD, PhD, a professor of pediatrics at Duke University School of Medicine, notes that spacing out vaccines feels like a compromise to parents who struggle to navigate the complex web of vaccine information they access online. “You’re trying to decide what’s right for your child. You go onto the Internet. You read different things. You try to decide whom to trust, but the sides of the argument can get pretty complicated,” he says. “One response is to pick what seems like an in-between, middle-of-the-road approach.”⁴

But, Dr. Baker notes, this approach can be problematic, not just because it puts children at risk of getting vaccine-preventable diseases during the delay, but also because it’s difficult for physicians and parents to keep track of alternate vaccine schedules. And, when it comes to vaccine protection, timing is everything.

Does One Size Fit All?

To make sure children receive their vaccines on time, CDC, AAP and the Academy of Family Physicians have established a recommended schedule of shots, with specific vaccines administered in a regular cadence from birth through 15 months. In a nutshell, the schedule recommends a total of 26 shots in the first 15 months of life,5 with a schedule of additional doses spaced out through age 12 years. The recommended vaccine schedule immunizes children from:

• Whooping cough (pertussis)

• Diphtheria

• Tetanus

• Mumps

• Measles

• Rubella

• Rotavirus

• Polio

• Hepatitis B

For parents who perceive that the recommended vaccine schedule seems excessive, AAP offers guidance on when a more flexible approach is acceptable in its FAQ response sheet: “The schedule is considered the ideal schedule for healthy children, but there may be exceptions. For example, your child might not receive certain vaccines if he or she has allergies to an ingredient in the vaccine, or if they have a weakened immune system due to illness, a chronic condition or another medical treatment. Sometimes a shot needs to be delayed for a short time, and sometimes not given at all.”⁶

But what about an approach that simply spreads the vaccines out over a longer period of time? Is there really any downside to taking things more slowly? AAP covers this question as well: “The recommended schedule is designed to work best with a child’s immune system at certain ages and at specific times. There is no research to show that a child would be equally protected against diseases with a very different schedule. Also, there is no scientific reason why spreading out the shots would be safer. But we do know that any length of time without immunizations is a time without protection.”⁶

Of course, not all pediatricians agree with AAP. In 2007, California-based pediatrician Robert Sears published The Vaccine Book: Making the Right Decision for Your Child, which seeks to address the biggest concerns of parents who are looking for a middle ground between the official CDC vaccine schedule and not getting any vaccines at all. Dr. Sears’ book includes an alternative vaccine schedule, which allows for fewer shots at each visit and sometimes pushes back specific vaccines for months or even years after the official schedule’s recommendations. “My main worry about [CDC’s] schedule is that there really hasn’t been enough research on the various chemicals and ingredients in many vaccines to prove that they are 100 percent safe,” he says. “It has also been my experience that giving five or six vaccines at a time can increase the likelihood of a severe reaction.”

Dr. Sears recommends an alternative vaccine schedule that spreads the shots out over a longer period of time, up to age 6 years. He also recommends not giving kids more than two vaccines at a time, and his schedule changes the order of vaccines, prioritizing what Dr. Sears believes are the most crucial vaccines, based on how common and severe the diseases are. The advantage, he says, is that his alternative schedule won’t overwhelm young immune systems, but it still provides complete vaccine protection. “If some of the theoretical problems with vaccines are real, this schedule circumvents most of them,” he explains. “If the problems aren’t real, then the only drawback is the extra time, effort and cost for the additional doctor’s office visits.”⁷

Arguments Against the “A-la-Carte” Approach

A 2009 article in Pediatrics, the official journal of AAP, takes issue with Dr. Sears’ vaccine advice, stating that he misrepresents data about vaccine science and essentially misinforms parents. “He believes that parents’ fears should be indulged by offering alternative schedules, not countered by scientific studies, and he fails to explain that good science is the only way to determine whether a vaccine causes a particular adverse event,” the article reads. “A vaccine either causes a problem or it does not.”⁸

AAP also says the required extra visits to the pediatrician (five for the CDC’s schedule versus a dozen for Dr. Sears’ schedule) will discourage compliance and leave children potentially vulnerable to vaccine-preventable diseases.

With so many varying opinions, both sides of the argument agree that parents hoping to make the right decision for their child should pursue due diligence by educating themselves on the topic. Dr. Sears’ website states: “Before proceeding with the full regular vaccine schedule, I encourage parents to become fully informed about each disease and vaccine so they can understand the safest way to vaccinate their children.”⁷

Likewise, Children’s Hospital of Philadelphia encourages parents to think through their vaccine decisions thoroughly before committing to a schedule that contradicts CDC guidelines. An article on their website states: “Vaccines are added to the schedule based on when an infant is likely to be most susceptible to the disease. During the first few months of life, babies are somewhat protected from infectious diseases by maternal antibodies present in their bloodstream at birth or in their mother’s milk. However, protection afforded by maternal antibodies wanes during the first year of life and is somewhat variable.”⁹

The article goes on to say that since the length of protection and robustness of the maternal response cannot be predicted, eliciting the infant’s own immune response before the maternal response wanes is the most conservative approach when it comes to vaccinations.

According to nurse practitioner Erin Gennocro, APRN, of Weiss Pediatric Care, one of the biggest concerns she hears from vaccine-hesitant parents is that there are too many vaccines given at a time, which may overload their child’s immune system. Those fears, she says, are unfounded. “If a parent has concerns about the safety of vaccines, instead of focusing on vaccinations themselves, parents need to focus on learning about the disease.”⁹

To Delay or Not to Delay: Comparing the Numbers

On the delayed vaccine schedule, children are immunized against eight diseases by 15 months of age. They will not be immunized against measles, rubella, chickenpox, Hepatitis A or B. Children on this delayed schedule receive a total of 17 shots and visit the doctor’s office nine times, nearly twice as many visits as compared to the CDC schedule.

By comparison, when a child is vaccinated by the CDC’s recommended schedule, they are immunized against 14 diseases by age 2 years. With this schedule, babies see their doctor five times in the first 15 months of life and receive as many as 18 shots (when using combination vaccines), or as many as 26 shots when using individual antigens.¹⁰

So where does that leave us? A study published in March 2020 in Pediatrics found one-third of parents in the United States are now choosing to delay vaccinations for their young children. The findings, it says, are consistent with several trends reported by American doctors in recent years, including parental requests to limit the number of vaccinations given at each visit, increased need for a strong and consistent physician recommendation for vaccination, and potentially wavering vaccine confidence. “The findings in this study reaffirm that deviations from the recommended immunization schedule, whether as the result of parents following an alternate schedule or other factors, result in many children remaining out-of-date for an extended period of time,” say the study’s authors.

The study’s authors concluded that although a majority of U.S. children adhere to a recommended vaccination schedule for early childhood immunizations, adherence differs by key sociodemographic characteristics, and future research should focus on identifying the parent actions and circumstances that increase the likelihood of deviating from the recommended schedule. Interventions, they say, should target both providers (to ensure all eligible vaccines are offered) and parents (to ensure all eligible vaccines are received), ultimately contributing to greater numbers of U.S. children who are protected and up-to-date on all recommended childhood immunizations.¹¹