When a child is born, she usually has immunity to certain diseases. This is a result of the disease-fighting antibodies that have passed through the placenta from the mother to the unborn child. After birth, the breastfed baby gets the continued benefits of additional antibodies in breast milk. But in both cases, the immunity is only temporary.

Immunization (vaccination) is an artificial way of creating immunity to certain diseases - by using relatively harmless substances called antigens that come from or are similar to the components of microorganisms that cause the diseases.

Microorganisms can be viruses, such as measles virus, or they can be bacteria, such as pneumococcus. Vaccines stimulate the immune system into reacting as if there were a real infection. The immune system then fights off the "infection" and remembers the organism so it can fight it off quickly if it enters the body at some future time.

Some parents may hesitate to give their children a vaccine because they are concerned about complications or their children developing the illness the vaccine is supposed to prevent. Although it's true that some vaccines could have these effects, the likelihood of that happening is very small. Not immunizing your child exposes her to greater health risks associated with contracting the disease the vaccine is intended to prevent.

Immunization is one of the best means of protecting your child against contagious diseases. The following vaccinations and schedule are recommended by the American Academy of Pediatrics (AAP). Please note that some variations are acceptable and that changes in recommendations frequently occur as new vaccines are developed; your child's doctor will determine the best vaccinations and schedule for your child.