Whose vaccine helped end smallpox?

The English physician Edward Jenner is credited with creating the first successful vaccine, in 1796, when he observed that milkmaids who caught the mild disease cowpox seemed protected from deadly smallpox. He tested his idea by deliberately exposing a young boy to cowpox and then to smallpox, and the boy did not fall ill. The word vaccine comes from vacca, the Latin for cow, in honour of this origin. Building on Jenners work, a worldwide vaccination campaign led by the World Health Organization eradicated smallpox entirely, with the last natural case recorded in 1977 — the only human disease ever to be completely wiped out.