Immunization, or vaccination, is a way to create immunity to certain diseases. This is done by using small amounts of a microorganism that causes the particular disease. The microorganisms used in immunization have been killed or weakened already, but when used in a vaccine, stimulate the immune system to react as if they were a strong infection. The immune system then fights to protect the body from the "infection" and remembers the microorganism so that it can fight it quickly if it enters the body in the future.
Some parents may hesitate to have their kids vaccinated because they're worried that the children will have serious reactions or may get the illness the vaccine is supposed to prevent. Because the components of vaccines are weakened or killed — and in some cases, only parts of the microorganism are used — they're unlikely to cause any serious illness. Some vaccines may cause mild reactions, such as soreness where the shot was given or fever, but serious reactions are rare. The risks of vaccinations are small compared with the health risks associated with the diseases they're intended to prevent. When any immunization is given, a sheet with full disclosure about the vaccine is given to you for your review.
There are many immunizations that are required, recommended, or suggested for children. Talking to your pediatrician about your child's immunization schedule is the first step toward keeping your child and his or her immune system healthy and happy.