For centuries, smallpox took millions of lives. It was the deadliest disease. The current generations have not seen smallpox. Thanks to Edward Jenner and immunization efforts by World Health Organization we are free of this disease.
Jenner observed dairymaids who previously contracted cowpox, which caused blistering on cow’s udders, to have a unique protection against small pox.
To confirm this, on May 1976, Jenner inoculated matter from the cowpox lesions of the dairymaid , Sarah Nelms, into an 8-year-old boy, James Phipps. Phipps felt chills and lost his appetite nine days after the procedure but recovered entirely the following day. On July 1796, Jenner inoculated the boy again, this time with matter from a fresh smallpox lesion, no disease developed. Edward Jenner concluded the immunization was complete and was etched into history as ‘The Father of Immunology’.
Although Edward Jenner introduced the vaccine using the cowpox virus, it was replaced by the vaccinia virus.