Inoculation
China may have used inoculation in the 10th century. The Emperor of China at the time lost his eldest son to smallpox. He wanted a way to help prevent smallpox from killing any more members of his family. He summoned many people from throughout the empire to attempt to find a cure to smallpox. A man carried out inoculation to Immunise his family. However, the source of the story was supposedly written 100's of years after the event.