The World Health Organization officially certified that after a number of concentrated vaccination campaigns around the world smallpox had been eradicated. Only two infectious diseases have been completely eradicated in history; the other is Rinderpest, which is an infectious disease of cattle that was eradicated in 2011.
The origin of smallpox is unknown; however, the earliest evidence of the disease dates to the 3rd century BCE in Egyptian mummies. The disease historically occurred in outbreaks. In 18th-century Europe, it is estimated that 400,000 people died from the disease per year, and that one-third of all cases of blindness were due to smallpox. Smallpox is estimated to have killed up to 300 million people in the 20th century and around 500 million people in the last 100 years of its existence, as well as six monarchs. As recently as 1967, 15 million cases occurred a year.