It's Safe to Follow the Vaccine Schedule for Babies. Here's Why.

An increasing number of parents are concerned about vaccinating their children, questioning doctors about the necessity and safety of following the immunization schedule recommended by the Centers for Disease Control and Prevention (CDC). However, decades of studies have demonstrated that vaccines are safe and that administering vaccines according to CDC guidelines is critical for building immunity in young bodies, experts told Live Science.

Parents worried about vaccines tend to ask similar questions, said Dr. Robert Jacobson, a physician in pediatric and adolescent medicine with the Mayo Clinic in Minnesota. They want to know if it's more painful to get three or four shots at once, if the baby's immune system can tolerate multiple vaccines, and what might happen if the vaccines are delayed. 

"Other issues are distrust in the health system [and] the government," said Heidi Larson, an anthropologist with the London School of Hygiene and Tropical Medicine and the director of the Vaccine Confidence Project, which studies people's views on immunization. 

These fears may prompt parents to eliminate or delay vaccinations, but such a course can jeopardize an infant's health and raise their risk of contracting a preventable and potentially life-threatening disease, according to the CDC. 

Related: Can You Still Get the Measles If You've Been Vaccinated?

Is it really more painful for babies to get multiple shots in one visit? No — on the contrary, studies have found that infants experience more pain when distressing medical procedures are spread out over several days, compared to when multiple procedures are performed on the same day, Jacobson said. 

In newborns exposed to multiple heel lances — blood collection through puncture — over the course of several days, the drawn-out, painful interventions heightened anxiety and anticipation of pain, researchers reported in 2002 in the journal JAMA.Those babies "learned to anticipate pain and exhibited more intense pain responses" during procedures than infants who did not receive repeated jabs.  

As for multiple vaccines, the recommended combinations do not overwhelm, weaken or "use up" babies' immune systems, as some parents fear; in fact, the multiple shots ultimately strengthen a baby's natural resistance to pathogens, researchers reported in 2002 in a study published in the journal Pediatrics.

"Young infants have an enormous capacity to respond to multiple vaccines, as well as to the many other challenges present in the environment," the scientists wrote in the 2002 Pediatrics study. "By providing protection against a number of bacterial and viral pathogens, vaccines prevent the 'weakening' of the immune system and [the] consequent secondary bacterial infections occasionally caused by natural infection."

A race against time

As for putting off scheduled immunizations, waiting to give vaccines may actually be dangerous to a baby's health.

Such delays can be risky because children need a given vaccine before their first encounter with the disease, Jacobson said. "If this schedule is designed as a race against time to protect the child before they're exposed, the delayed schedule actually increase[s] the chance the child will get the illness before they get the vaccine," he said.

Adding time between doses could mean some vaccines are given too close in time to other scheduled vaccines, so the child's immune system may not respond to either vaccine and will instead ignore them completely. This could cancel out the effectiveness of both immunizations, leaving the child vulnerable to illness.

When vaccinating babies and young children, timing is critical, Jacobson said. For example, a baby may get some immunity against the flu from its mother; a flu vaccine won't work until that protection fades. Other vaccines, such as the inoculation for rotavirus, cannot be given after a child reaches a certain age. Infants get two or three doses of rotavirus vaccine, but after babies reach 8 months old, these vaccines carry an increased risk of a condition called intussusception, when one segment of the intestine "telescopes" inside another segment, potentially leading to an obstruction.

What's more, when parents opt for a delayed vaccination schedule, they rarely follow it. In children born in Portland, Oregon, between 2003 and 2009, only about 1% of parents who postponed their children's vaccines actually followed the altered schedule, according to a study published in 2012 in the journal Pediatrics. 

"It's hard work bringing your children in repeatedly to doctors' visits," Jacobson said. "Everything from scheduling to parking makes it even more complicated, and your children's own lives and your own lives get in the way."

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Originally published on Live Science.