Daring Medical Experiment...

On May 14, 1796, one of the most daring medical experiments in history commenced when an English physician named Edward Jenner intentionally infected a young boy with the disease cowpox.

Jenner (1749-1823) was a country doctor with an excellent reputation. His particular fascination was smallpox, a disease that had been ravaging Europe for centuries. The vast majority of the population contracted smallpox; in some epidemics it was fatal to one-third of the victims. Many survivors were left with scarred and disfigured faces.

It was well known that a person who survived a mild case of smallpox would thereafter be immune. But the frequent attempts to inoculate against the disease were unscientific and sometimes fatal.

Jenner began to investigate a folk belief that dairymaids who contracted another disease, cowpox, never got smallpox. Cowpox is a cattle disease that resembles smallpox; it was occasionally transmitted to humans but never deadly.

So 214 years ago, Jenner found a milkmaid, Sarah Nelmes, who had cowpox. He took some fluid from a cowpox pustule on her hand and injected it into the arm of a volunteer, local eight-year-old James Phipps.

If Jenner's experiment failed, his name would live in infamy. Instead, it was a great success: when Jenner later inoculated the boy with smallpox he showed no symptoms.

Thus was born the study of immunology. The procedure Jenner invented, vaccination spread quickly, even though for decades no one would understand why it worked. Jenner became a hero in his own lifetime and smallpox became the first disease defeated by medicine.