The Probert Encyclopaedia of Medicine

COWPOX

Cowpox is a contagious viral disease of cows characterised by vesicles on the skin, particularly on the teats and udder. Edward Jenner popularised the incorrect notion that persons who had contracted cowpox were immune from contracting smallpox (based on a solitary example of a boy whom, having been deliberately infected with cowpox was later injected with smallpox and found not to contract the disease). In reality, however, no such correlation exists.
Research Cowpox