This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Before Edward Jenner tested cowpox material on eight-year-old James Phipps in May 1796, the only known defense against smallpox was variolation, deliberate infection with scab material taken from an infected person. Variolation was practiced in China as early as around 1000 CE and reached Europe in the early eighteenth century through travelers arriving from Istanbul. The trial conducted by Jenner showed that cowpox exposure, a far milder disease, produced immunity to smallpox without the risk carried by variolation, and by 1803 the method had been translated into French and Spanish and adopted for vaccination campaigns as far as the Americas and the Far East. Medical historians continue to debate how credit for founding immunization should be divided: the 1796 trial gave the practice a documented scientific method and the name vaccination, but variolation had already demonstrated the underlying principle, deliberate mild exposure producing immunity, for centuries in a tradition Western medicine did not originate. Reading the history honestly means holding both facts at once rather than crediting a single inventor.