The word “vaccine” literally comes from cows.
In 1796 Edward Jenner transferred cowpox material to an 8-year-old boy, who then proved immune to deadly smallpox. “Vacca” is Latin for cow – hence “vaccine”. Smallpox killed around 400,000 Europeans a year in the 18th century. In 1980 the WHO declared it eradicated.
Useful: Smallpox remains the only human disease ever wiped out worldwide by vaccination.
Source: en.wikipedia.org