Edward Jenner (1749-1823), British physician. Jenner, who also did work as a naturalist, is famed for developing a vaccine for the often fatal viral infection smallpox. He investigated folk tales about the immunity of cowpox victims to smallpox. In 1796 he used a thorn to inoculate a healthy boy with fluid from a cowpox blister on a dairy maid's finger. Six weeks later he inoculated the boy with smallpox, and the boy did not develop the disease. The immunising process was named vaccination after the cowpox virus (vaccinia), and was made compulsory in Britain in 1853. Jenner was elected Fellow of the Royal Society in 1788 for his work on the cuckoo.