In which year was small pox vaccine discovered?

The smallpox vaccine was first discovered in 1796 by the British physician Edward Jenner. Jenner observed that milkmaids who had contracted cowpox, a milder disease than smallpox, did not seem to be susceptible to smallpox. He hypothesized that cowpox could be used to protect against smallpox and tested his theory by inoculating a young boy with cowpox and later exposing him to smallpox. The boy did not develop smallpox, proving Jenner's hypothesis.

Jenner's discovery revolutionized the field of medicine, leading to the development of the first vaccine and paving the way for the eradication of smallpox. In 1980, the World Health Organization declared smallpox eradicated, making it the first and only human disease to be eradicated through vaccination.