A Columbia Pediatrician Explains Childhood Vaccination Safety and Schedule

As possible changes to the current childhood vaccination schedule make headlines, parents may have new questions about some of our most common immunizations. It’s important for families to understand that despite recent news headlines, the science behind vaccine safety and schedule remains unchanged.

“There is no scientific evidence that separating vaccines or unnecessarily spacing them out makes vaccination safer for children,” says Columbia pediatrician Melissa Stockwell, MD, MPH. “Instead, delaying vaccines can leave children unprotected against serious diseases for longer periods of time.”

Dr. Stockwell, chief of the Division of Child and Adolescent Health at Columbia, addresses vaccine basics, as well as current issues around spacing vaccines, separating the combined MMR (measles, mumps, rubella) vaccine, and more.

Are vaccines safe for my child?

Yes. Vaccines recommended for children are extensively studied for safety and effectiveness, and vaccine safety continues to be monitored after vaccines are approved. Most vaccine side effects—such as soreness at the injection site, fatigue, fussiness, or a low-grade fever—are mild and temporary.

Is it safe for children to receive multiple vaccines at the same time?

Yes. Children’s immune systems are capable of responding to multiple vaccines at once.

In fact, the number of antigens (the proteins and sugars that trigger an immune response) in vaccines is small compared with what children encounter naturally.

Across routinely recommended vaccines, children are exposed to about 160 to 170 antigens. By contrast, a single bacterium can contain thousands. An ordinary bacterial infection, like an ear infection or strep throat, can therefore expose a child’s immune system to far more antigens than all doses of all recommended vaccines combined.

Combination vaccines also reduce the number of injections children need while allowing them to receive protection at the most effective time.

Can I space out my child’s vaccines or follow an alternate schedule?

There is no evidence that spacing vaccines further apart makes vaccination safer.

The childhood vaccination schedule is carefully designed around when children are most vulnerable to particular diseases, as well as how their immune systems respond to vaccines. Delaying or spacing vaccines unnecessarily increases the amount of time a child remains susceptible to infection.

Outbreaks also show why timely vaccination matters. Children can encounter vaccine-preventable diseases in places families may consider low risk. The ongoing resurgence of measles in the United States makes timely protection particularly important.

Delaying vaccination does not make vaccination safer. It leaves children unprotected for longer.

Is it safer to separate the MMR vaccine into three individual shots?

No. There is no established clinical or immunological benefit to separating the measles, mumps, and rubella vaccines.

The combined MMR vaccine has been extensively studied and used for decades. Separating it into three shots would mean additional injections and potentially additional appointments without providing a clinical benefit.

It could also increase the likelihood of missed or delayed doses, extending the amount of time a child is unprotected.

And the diseases themselves can be serious. Measles can cause pneumonia and encephalitis (inflammation of the brain). Mumps can cause hearing loss and reproductive complications. Rubella is particularly dangerous during pregnancy because infection can cause miscarriage, stillbirth, or severe birth defects.

Could giving vaccines separately mean more doctor visits?

Potentially. Requiring separate shots that are spaced out across additional appointments could create practical challenges for families. Parents may have to take time off from work, arrange transportation, or find care for other children. More vaccine-only appointments could also put additional pressure on pediatric practices and make scheduling other types of care more difficult.

Is the amount of vaccine that children receive overwhelming to their bodies?

No. The actual physical volume of routine childhood vaccines is very small.

Using current combination vaccines, the total volume of routine early-childhood immunizations (excluding influenza and COVID-19) is about 2 teaspoons. If you add routine school-age and adolescent vaccines, the total is about 1 tablespoon over childhood and adolescence.

Even if you factor in annual influenza and COVID-19 vaccines from infancy through age 17, the cumulative volume over the course of an entire childhood is only a few tablespoons.

Do vaccines cause autism?

No. Decades of research have found no causal relationship between vaccines and autism.

The original study that suggested a connection between the MMR vaccine and autism was retracted after serious problems with the research were identified. Numerous studies conducted since then have found no association between vaccination and autism.

Renewed public discussion about vaccines and autism does not change that scientific evidence. Pediatricians spend years training to evaluate scientific evidence, understand an individual child’s needs, and help families make informed decisions that are best for their child.

Amid public confusion over vaccines, what should parents do?

It is understandable for parents to be confused when communications from federal officials and medical organizations differ.

Parents should talk with their child’s pediatrician rather than delay vaccination while trying to sort through conflicting information themselves. Pediatricians can explain the evidence behind vaccine recommendations, consider an individual child’s medical history, and help families decide how best to protect their child.

The purpose of the childhood vaccine schedule is straightforward: to protect children against potentially serious diseases before they encounter them.