smallpox

The first attempts to prevent smallpox were made in India as early as 1000 BC and involved either nasal insufflations of powdered smallpox scabs, or scratching material from a smallpox lesion into the skin.
If successful, the procedure produced lasting immunity to smallpox.
The smallpox vaccine was eventually perfected in 1796 by British doctor Edward Jenner, who discovered that immunity could be produced by inoculating a person with material from a cowpox lesion.