Those against vaccines argue that doctors have exaggerated the benefits of vaccinating against disease.They claim that the number of deaths from some diseases had fallen before vaccines were introduced to the world. There is also concern that vaccines may harm the body instead of helping it. Some also believe that vaccines can cause longterm problems with the immune system. It is true that some vaccinations are not entirely safe. Up to ten percent of all people who get a vaccine may not develop immunity. Some of those people might also experience bad reactions to vaccines.