Cowpox to the mild form of smallpox and the observation that dairy farmers were immune from smallpox inspired the first smallpox vaccine, created and administered by English physician Edward Jenner. The word “vaccination,” coined by Jenner in 1796, is derived from the Latin root "vaccinus", meaning of or from the cow. Once vaccinated, a patient develops antibodies that make them immune to cowpox, but they also develop immunity to the smallpox virus, or "Variola virus". The cowpox vaccinations and later incarnations proved so successful that in 1980, the World Health Organization announced that smallpox was the first disease to be eradicated
Smallpox disease continued to diminish in the wealthy countries. In Northern Europe a number of countries had eliminated smallpox by 1900, and by 1914, the incidence in most industrialized countries had decreased to comparatively low levels. Vaccination continued in industrialized countries, until the mid to late 1970s as protection against reintroduction. Australia and New Zealand are two notable exceptions; neither experienced endemic smallpox and never vaccinated widely, relying instead on protection by distance and strict quarantines. The first hemisphere-wide effort to eradicate smallpox was made in 1950 by the Pan American Health Organization. The campaign was successful in eliminating smallpox from