In 1979, the World Health Organization announced the eradication of smallpox in the world. The use of vaccines has drastically improved people's health around the world. Vaccination evolved from inoculation, an old medical practice dating back to China in the fifteenth century. Interestingly, although people in the past did not fully understand viruses, inoculation utilizes the same principle as vaccination by pre-exposing a healthy individual to small amounts of viruses to allow the body to naturally gain immunity to the viruses. One may ask, if people in the past practiced inoculation, why did diseases, such as smallpox, still spread widely around the world and caused thousands of deaths? First, in his essay "The Inoculation Controversy in Boston: 1721-1722," John B. Blake's discusses how Bolyston, a physician, came to adopt inoculation and how people reacted to the adoption. Second, Everett M. Rogers’explains the three properties of innovation in his…