Adopted from the French, it is a technique originally revealed in 1796 by the ingenious English doctor and researcher Edward Jenner (1749-1823) in view of the looming threat of smallpox. The name comes from the particular manifestation of a virus that existed among cows, known scientifically as variolae vaccinae (popularly known in English as cowpox), from the Latin vaccinia, associated with the adjective vaccinus, understanding anything related to cows, coming from vacca, for “cow” specifically. Later, in 1891, the French physicist Louis Pasteur used the term vaccination in recognition of Jenner, in the fight against anthrax, as well as avian cholera.

Jenner, recognized as a member of the Royal Society for his work as a naturalist on the behavior of the cuckoo (bird species), developing a wide experience in the field of biology and at a surgical level from working in London with surgeon John Hunter, discovered that a group of women who milked cows contracted a mild version of the virus through contact with that animal, and decided to run an experiment in May 1796 by taking a sample of the wounds of a worker, Sarah Nelms, to intentionally infect an eight-year-old boy, James Phipps, who had a series of reactions such as fever and dizziness that quickly passed, and who six months later would be exposed to human smallpox to prove that he was in fact immunized. He presented his findings to the Royal Society in 1797; however, it would be rejected for lack of sufficient evidence, which is why Jenner continued working to present his results again the following year being validated on this occasion.

Around 1800, the smallpox vaccine embraced all of Europe and the world, marking one of the greatest findings towards modern medicine and the understanding of the immune system, from injecting a controlled sample of a virus in the body to activate the creation of antibodies capable of facing the most invasive types in case they come into contact. In December 1979, smallpox was eradicated, with one last case reported in Somalia.