The practice of preventing the disease by scratching the skin with an infected needle, developed early on in China, was introduced to Europe via the Ottoman Empire in the mid-eighteenth century. Its treatment was revolutionized at the end of the century, in 1798, by an English country doctor, Edward Jenner (1749–1823), who noticed that milkmaids never caught smallpox, and concluded that the reason for their immunity was because they had already caught a related disease, cowpox, which did not pose any threat to humans. Jenner’s new preventive treatment, which he called vaccination, after the
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