Vaccine-Preventable Diseases

No. Vaccines "strengthen" the immune system to help protect children and adults from certain diseases without causing the suffering of the disease itself.

Vaccines contain either non-infectious parts of the germ responsible for an infection or, in some cases, the whole germ that has been altered (killed or weakened). The administration of a vaccine causes the body to respond by creating immune defense (antibodies and white blood cells) against the germ the same way the natural infection would. However, with vaccination, the amount of exposure to the germ is controlled; protection can therefore be established in most individuals without causing the illness normally seen with the infection. The next time the vaccinated person is exposed to the same germ, the antibodies can recognize and destroy it without causing an infection. Vaccination however may not result in protection of all healthy individuals. Some vaccines, like VARIVAX^® III, should not be given to patients with weakened immune systems.

Scientists estimate that the immune system can identify and respond to numerous (hundreds of thousands) different germs. The vaccines that are recommended for children and adults use only a limited portion of the capacity of the immune system.