Smallpox one-third of the cases resulted in blindness. These deaths included those of four reigning monarchs and a queen consort. In the 20th century smallpox killed 200-300 million people. Edward Jenner discovered in 1798 that vaccination could prevent smallpox. In 1967, the WHO intensified efforts to eliminate the disease. Smallpox is one of two infectious diseases to have been eradicated, the other being rinderpest in 2011. The term "smallpox" was first used in Britain in the 15th century to distinguish the disease from syphilis, which was then known as the "great pox". Other historical names for the disease include pox, speckled
Vaccination policy de Janeiro, Brazil, following an urban renewal program that displaced many poor, a government program of mandatory smallpox vaccination triggered the Vaccine Revolt, several days of rioting with considerable property damage and a number of deaths. Compulsory vaccination is a difficult policy issue, requiring authorities to balance public health with individual liberty: "Vaccination is unique among de facto mandatory requirements in the modern era, requiring individuals to accept the injection of a medicine or medicinal agent into their bodies, and it has provoked a spirited opposition. This opposition began with the first vaccinations, has not ceased, and probably never will.