Which scientist developed the first successful smallpox vaccine in 1796?

Edward Jenner developed the first successful smallpox vaccine in 1796.

Jenner was an English physician working in Gloucestershire. He noticed that milkmaids who had caught the relatively mild disease cowpox rarely developed smallpox, a far more dangerous infection. To test the idea, he inoculated James Phipps, an eight-year-old boy, with material from a cowpox sore and later observed that the boy resisted smallpox exposure.

The experiment helped establish vaccination as a practical medical method. The word “vaccine” comes from vaccinia, the scientific name associated with cowpox. Jenner did not understand viruses or the immune system in modern terms, and his methods would not meet current research standards, but his observation and controlled challenge were historically important.

A common mix-up is crediting Louis Pasteur with the first vaccine. Pasteur later developed important vaccines, including those for anthrax and rabies, and helped popularize the broader scientific theory of vaccination.