The setting was Gloucestershire, England, in 1796. It is hallowed ground well-trodden in the history books. Dr. Jenner noticed that the cow’s milkmaids had pustules but didn’t seem to get the deadly disease. From a cowpox lesion of a milkmaid, he poisoned an eight-year-old boy. The boy lived. Somehow this cowpox strain was the right varietal to spark an immune system defense. Happy birthday, world’s first vaccine!
