Smallpox

Fascinating accounts have been written describing ways in which different peoples tried to vaccinate themselves against smallpox. In China, India, and the Americas, from about the tenth century, it was noted that individuals Smallpox on the arm of a man in India. Photograph by C. James Webb. Phototake NYC. Reproduced by permission.
who had had even a mild case of smallpox could not be infected again. Material from people ill with smallpox (fluid or pus from the papules, the scabs) was scratched into the skin of people who had never had the illness, in an attempt to produce a mild reaction and its accompanying protective effect. These efforts often resulted in full-fledged smallpox, and probably served only to help effectively spread the infection throughout the community. In fact, such crude vaccinations against smallpox were against the law in Colonial America.

In 1798, Edward Jenner published a paper in which he discussed his important observation that milkmaids who contracted a mild infection of the hands (called cowpox, and caused by a relative of variola) appeared to be immune to smallpox. He created an immunization against smallpox that used the pussy material found in the lesions of cowpox infection. Jenner's paper led to much work in the area of vaccinations and ultimately resulted in the creation of a very effective smallpox vaccine, which utilizes the vaccinia virus-another close relative of variola.