Vaccines are medications that are designed to stimulate the body's immune system to generate a response that will protect the individual from the disease. The first vaccination was performed by Edward Jenner who had noticed that dairymaids who had had cowpox infection (Vacca = cow in Latin) did not succumb to the deadly smallpox infection that was claiming many lives at the time.

To test his theory, Jenner infected his gardener's son, James Phipps, with cowpox and then weeks later attempted to infect him with deadly smallpox. Happily, James survived the experience and was protected from infection and thus the practice of vaccination was born.