Which was the first Vaccine ever ?

The first vaccine developed was of smallpox. Edward Jenner, a British Scientist who is also known as father of immunology, developed the vaccine. In the last years of the 18th century, smallpox was the most deadly disease killing a large number of children. Edward experimented on a 14 years boy suffering from smallpox based upon folklore that milkmaids who suffered the mild disease of cowpox never contracted smallpox. Edward inserted pus taken from a cowpox pustule in the boy’s arm. Consequently, he proved that having been inoculated with cowpox Phipps was immune to smallpox. Edward Jenner also coined the term vaccine. Vacca means cow.
Time Line : Vaccine Development