"The health benefits associated with relatively recent advances in vaccine therapy are well documented.To mention just a few: in 1921 there were nearly 207,000 reported cases of diphtheria in the United States. In 1991, there were two. In the same year, apart from a small number (five to ten) of vaccine-associated cases, there were no reported cases of poliomyelitis, as compared with more than twentyone thousand in 1952; “The CDC projects that the world will be polio-free by 2003."