Edward Jenner was a scientist sometimes known as the Father of Immunology. Jenner's biggest contribution to the world of immunology was his vaccine against smallpox. In the late 1700's Jenner noticed that milkmaids did not contract smallpox, a deadly disease that killed one out of every three people and also left survivors maimed.
Jenner was not only a scientist; he was a physician who after training to become a doctor spent time as an army surgeon. He then went on to spend his time as a country doctor in England. His research into smallpox came from his case studies and clinical observations that he made. Jenner's research ended up preventing him from running his regular medical practice, but he received monetary support from colleagues and Parliament in order to continue his research.
Jenner observed that pus from blisters in milkmaids who developed the less deadly cowpox was somehow protecting these women from the more virulent smallpox. In 1796, Jenner tested his theory by injecting pus from cowpox into an eight-year-old boy's two arms. The boy was inoculated again and later tested, but showed no signs of disease. Jenner himself coined the word vaccination, after his work with cowpox was so successful against smallpox.
Louis Pasteur was a chemist and microbiologist who solved some of the greatest mysteries of microbiology. He worked with anthrax, rabies, chicken cholera and diseases in silkworms and helped to contribute to the development of many vaccines. Pasteur also described the scientific method for fermentation and the brewing of beer. Through his research, Pasteur discovered that microorganisms were responsible for the fermentation process. He also discovered that the growth of some organisms led to the spoiling of milk, wine and beer. He soon found a way of heating liquids that disposed of these microorganisms and thus to the process of Pasteurization.
Later, Pasteur worked with chicken cholera, finding that a weakened source of the cholera bacteria did not cause the disease in the chickens. By inoculating other chickens with the bacteria, he found they got slightly ill, but recovered. He followed this work up with his anthrax work with cattle. Pasteur found that by treating the anthrax bacteria with oxygen, its virulence decreased. Pasteur called his altered forms of bacteria, vaccines.
Pasteur used his rabies "vaccine" on a small child who had been bitten by a rabid dog. Although he was taking a great chance, he knew that without his "vaccine" the child would probably die. Pasteur's vaccine was a success and the child did not get rabies. After the success of the boy's treatment, the first of Pasteur's institutes was built. The success also laid the groundwork for other successful vaccines.