Whose vaccine helped defeat smallpox?

In 1796, English physician Edward Jenner performed a landmark experiment: noticing that milkmaids who caught the mild cowpox seemed immune to deadly smallpox, he deliberately inoculated a boy with cowpox and showed it protected him from smallpox. This was the first vaccine — the word itself comes from “vacca,” Latin for cow. Jenner’s technique spread worldwide and became the model for immunization. Building on nearly two centuries of vaccination, a massive global campaign led by the World Health Organization succeeded in eradicating smallpox entirely; the last natural case occurred in 1977, and the disease was declared eradicated in 1980 — the only human disease ever wiped out.