Final answer:
Edward Jenner is credited with the development of the modern smallpox vaccine in 1796, utilizing material from cowpox lesions to confer immunity, leading to the term vaccination derived from 'vacca' meaning cow.
Step-by-step explanation:
Edward Jenner was responsible for the development of the smallpox vaccine. Observing that milkmaids who had suffered from cowpox were not getting smallpox, Jenner hypothesized that cowpox could confer immunity against smallpox. In 1796, he conducted an experiment where he inoculated a young boy with material from cowpox lesions and later confirmed the boy was protected against smallpox. This breakthrough led to the modern practice of vaccination, a term stemming from the Latin 'vacca' for cow, due to the use of cowpox in preventing smallpox.
Vaccine development did not stop with Jenner's success. Another milestone was achieved by Louis Pasteur, who later developed vaccines for rabies, cholera, and anthrax. The victory over smallpox represented one of the pivotal moments in medical history, leading to a cascade of vaccine developments for various diseases over the centuries.