Smallpox 1718. In 1721, Cotton Mather and colleagues provoked controversy in Boston by inoculating hundreds. In 1796, Edward Jenner, a doctor in Berkeley, Gloucestershire, rural England, discovered that immunity to smallpox could be produced by inoculating a person with material from a cowpox lesion. Cowpox is a poxvirus in the same family as variola. Jenner called the material used for inoculation vaccine, from the root word "vacca", which is Latin for cow. The procedure was much safer than variolation, and did not involve a risk of smallpox transmission. Vaccination to prevent smallpox was soon practiced all over the world. During the
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.