Smallpox, from inoculation to eradication

To give a healthy child smallpox on purpose, Chinese doctors ground the dry scabs of a mild case into powder and blew it into the child's nose through a bent silver tube. A Qing court medical book of 1742 sets out the method.

The variola virus caused smallpox. In its common severe form about one in four of those who caught it died; most survivors kept pitted scars. Survivors never caught it again, and smallpox caught through a scratch in the skin was milder. Giving it on purpose was called inoculation, now variolation. Commonly 0.5 to 2 percent of those inoculated died, against 20 to 30 percent of those who caught it naturally. But inoculated people could spread full smallpox. Variolation may have arisen separately in China and India. In China it seems to have begun in secret around 1000 and appeared in medical books by about 1500. It was known in North and West Africa at least from the late 1600s; whether it began there or arrived from elsewhere cannot be known.

Reports of Chinese and Turkish methods reached London's Royal Society between 1700 and 1716. Lady Mary Wortley Montagu learned of it in the Ottoman Empire; in 1721 her daughter was inoculated in Britain. In Boston that year, Cotton Mather, who had learned of it from enslaved Africans, persuaded Dr. Zabdiel Boylston to try it. Six of the 244 people inoculated died, against about 14 percent of natural cases. On May 14, 1796, Edward Jenner put matter from a cowpox sore into a boy, James Phipps. When Jenner later inoculated him with smallpox, Phipps did not take it. This vaccination rarely spread to others.

In 1967, when smallpox was still endemic (always present) in 31 countries or territories, the World Health Organization began an intensified campaign. The last natural case was Ali Maow Maalin, a hospital cook in Merca, Somalia, who fell ill in October 1977. On May 8, 1980, the World Health Assembly declared the world free of smallpox.

The Great Epidemic of 735–737 and How to Care for the Sick in the Epidemic of 737 record a Japanese epidemic most historians identify as smallpox; The Smallpox in Mexico, 1520 recalls its arrival in Mexico. Planting Smallpox, Engrafting against Smallpox, and What the Africans of Boston Knew about Inoculation describe inoculation. A Sermon against Inoculation argues against it, and Instructions for Vaccine Inoculation gives Jenner's method.