Smallpox was a deadly, contagious virus that left survivors scarred and often blind. A smallpox vaccine was developed in 1796, but the disease wasn't officially eradicated until 1980.
Smallpox is a great example of what vaccination campaigns can accomplish. During the 20th century, there were as many as 500 million deaths from smallpox. It was particularly dangerous for children, 80 percent of whom died from it after being infected. Smallpox was notable for the rash of pustules it caused on the skin, as well as a high fever and muscle pain.