Vaccines help children stay healthy. A young child’s immune system can ward off some minor illnesses, but it may struggle with more serious disease. This is particularly true for babies, who have not yet been exposed to many diseases in their short lives. Vaccines protect against certain illnesses that may also be harmful or even life-threatening to older children, teens, or adults; vaccination provides protection.

Administering vaccines at the recommended times helps keep children safe from severe illness. Many diseases that now can be prevented by vaccination often led to disability or death in children decades ago, before vaccines were available.

Vaccines also keep the general population healthier by providing what’s called “herd immunity.” When a majority of people are vaccinated against a specific disease, that vaccination level significantly reduces that disease’s ability to spread through the population. This protects the minority of people who are not vaccinated, including babies who are too young for certain vaccinations and children who are receiving chemotherapy and are unable to receive vaccines.

Vaccines are considered safe. Some may cause minor side effects, such as fever and pain at the injection site, for a day or two. However, the benefits of vaccination far outweigh the drawbacks—the serious illnesses vaccines protect against may lead to hospitalization, disability, or death.

Childhood immunization is the term that refers to vaccines that babies, children, and teens receive to protect them from serious diseases. The term “immunize” simply means that vaccines help protect children and adolescents against various diseases.

Vaccines activate the immune system, training it to fight off particular viruses or bacteria it may encounter. A vaccine may contain a weakened version of a virus or bacteria that causes disease. This material cannot make a person sick, but it can trigger a response from the immune system so it’s poised to fight back against that disease if it encounters it in the future.

People receive vaccines throughout their lives, from infancy through adulthood. Some vaccines, such as the flu shot, are intended to be given annually. Others may not be given again after childhood.

To become immune to certain conditions, babies need more than one dose of some vaccines. The timing and number of those immunizations are guided by the Immunization Schedules from the Centers for Disease Control and Prevention (CDC).

Most childhood vaccines are given by injection. When babies and toddlers are given vaccines by injection, the needle is inserted into the thigh. For children and teens, vaccines are injected into the upper arm, as with adults.

It’s possible for children to take certain immunizations by mouth. And one method for administering the flu vaccine is via nasal spray.

Your child’s pediatrician should keep you informed about the recommended schedule of vaccinations and will let you know when it’s time for your child to get their next vaccine. Vaccines are often administered at well visits, but it’s possible to schedule an appointment just for vaccination.

Yes, vaccines are safe for children.

Every year, the CDC, the American Academy of Pediatrics, and other medical organizations decide which vaccines should be listed on the recommended vaccine schedule for children. They make these decisions with child safety in mind.

Children may get short-lived side effects from vaccines, such as muscle aches, low-grade fever, or fussiness. These are not dangerous; they are signs that the vaccine is interacting with the child’s immune system and building protection.

In very rare instances, a child may have a negative reaction to a vaccine. However, adverse reactions tend to be less risky than exposure to vaccine-preventable diseases.

Vaccines are generally safe for healthy babies, children, and teens. If your child has an allergy, let your pediatrician know beforehand. Some vaccines may not be recommended for children who are allergic to eggs, latex, yeast, gelatin, or other substances.

If your child had a severe reaction to the first dose of a vaccine, let your pediatrician know. This may affect your child’s ability to get the next dose or doses of that vaccine.

If your child is sick on the day when they are scheduled to get vaccinated, ask the pediatrician whether or not the shot should be delayed. It may depend on the severity of your child’s illness.

“Many of the faculty members of the Yale Pediatric Infectious Disease Section are members of the organizations that study and review childhood immunizations and make recommendations for the yearly immunization schedule put forward by the CDC,” says Yale Medicine pediatrician Maryellen Flaherty-Hewitt, MD. “Primary care pediatricians working in the Section of General Pediatrics provide care to children from birth to young adulthood and are adept at having evidence-based discussions with patients and their families about the importance of childhood immunizations. Prevention of childhood disease through immunization is one of the most important jobs of the pediatrician.”