It’s recommended that children receive 25 immunizations by the time they’re 15 months old. That may seem like a lot of shots, but there’s a reason why certain vaccines are given at specific times in a child’s life—and why it’s so important to follow the recommended schedule.

“Your pediatrician doesn’t create their advice about vaccines from nothing,” says Dr. Pilar Bradshaw. The Advisory Committee on Immunization Practices and the Centers for Disease Control puts out well-studied information and updates every year to give us the very best research-based data on when to immunize and with which vaccines.”

How are the timing and spacing of shots determined?
According to the American Academy of Pediatrics, immunizations are scheduled based on the age when the body’s immune system works the best and will provide the earliest protection possible to infants and children.

“The reason that the immunization schedule is very heavily loaded toward babies is because those are the children who have the least natural immunity and the least ability to fight a disease,” Dr. Bradshaw says.

Why are three or more doses of some vaccines needed?
Part of the extensive research that is conducted for each vaccine includes figuring out how long its protection lasts. When a vaccine’s antibody levels drop, children need another “boost.” Some longer-lasting vaccines only need to be given twice, while others may need to be given upwards of five times in a child’s life and often within a closer timeframe.

Can shots be spread out over a longer period of time?
The simple answer is no, they cannot be spread out over a longer period of time, because delaying vaccines at the recommended age leaves children unprotected.

“There’s a reason the schedule is what it is, and if you delay it, you’re letting your kid’s antibody levels drop to a point where they are no longer optimally protected,” Dr. Bradshaw says.

Does it overwhelm a child’s immune system to give multiple shots in one visit?
This may be one of the most common myths when it comes to vaccines. The answer is no, it does not overwhelm a child’s immune system to give multiple shots in one visit. Infants and children are exposed to more germs every day, just by playing, eating and breathing than what is in any combination of vaccines on the schedule.

Immunizations remain important as children age
Another group of kids that health care providers should see regularly for immunizations is teenagers. They are at risk for dangerous illnesses, including human papillomavirus (HPV), which has been linked to numerous cancers in women and men, and meningitis, an inflammation of the membranes that surround the brain and spinal cord and protect the central nervous system. The HPV and Meningococcal B vaccines help reduce the risk of contracting these diseases.

If you have questions about vaccines for your child, talk with your pediatrician. To access the recommended immunization schedule, click here.