As you know, the benefits of any given treatment must be compared to any adverse side effects patients may experience. In the case of vaccines, the benefits are vast—the freedom from a plethora of often-fatal illnesses. The side effects, though, are minimal for healthy children. Furthermore, vaccines are subjected to strict tests by the FDA before they are ever allowed to enter the market. Vaccines have been around for many years, and have presented only a few minor problems, most of them with children who have pre-existing illnesses, such as allergies or leukemia.