Jenner

In 1980 the World Health Organization declared that the deadly disease smallpox had been eradicated, an accomplishment attributed to the success of the smallpox vaccine. The vaccine had been developed almost 200 years earlier by the British physician Edward Jenner, who had based his work on a piece of folk wisdom from the countryside that few doctors had taken seriously: people who caught cowpox, a mild viral infection of cattle, never got smallpox. In 1796 Jenner proved the truth of this scientifically in a famous experiment he conducted on an eight-year-old boy named James Phipps. Jenner exposed Phipps to a person with cowpox, then two months later exposed him to smallpox (this would be considered unethical by today's standards). As Jenner expected, the boy warded off the smallpox without any complications. Prior to this, there existed a form of vaccination against smallpox that consisted of exposing people to a mild form of the disease. Although this method often worked, it was risky, and the exposed person sometimes died. Jenner, who devised the word vaccination from the Latin vacca, for “cow,” is considered to be the father of immunology. He also did significant research on heart disease.