Vaccination is a term coined by Edward Jenner for the process of administering a weakened form of a disease to patients as a means of giving them immunity to a more serious form of the disease. Vaccination (Latin: vacca—cow) is so named because the first vaccine was obtained from cows: the cowpox virus, a relatively benign virus that was discovered to have the side effect of conferring immunity to smallpox, a deadly and highly contagious disease.