vaccine [L18th] The English physician Edward Jenner (1749–1823) knew the folk tradition that milkmaids did not catch smallpox, and speculated that this might be because they had come into contact with the virus causing cowpox, a disease whose effect on humans resembles mild smallpox. In 1796 he deliberately infected an eight-year-old boy, James Phipps, with small amounts of cowpox, and when the medical world rejected the successful result he repeated the experiment on several other children, including his own baby son. In 1798, writing in Latin, Jenner referred to cowpox as variolae vaccinae, from vaccus ‘cow’, and the beginning of the 19th century saw the words vaccine, vaccinate, vaccination, and the beginning of the end of a deadly and disfiguring disease.