Monday, 24 August 2015

Cowpox, Smallpox, and "Vaccination"

The terms "vaccine" and "vaccination" derive from the Latin "vacca" for cow. The reason is that the first effective vaccine used pus from a mild skin disease, so-called cowpox, to immunize people against the deadly smallpox. "Cowpox" was actually horse-pox, which sometimes infected cows. 

The cartoon below by James Gillray, c. 1800, shows Edward Jenner, usually given credit for the procedure, vaccinating people, who are turning into cows. Although satire, the cartoon shows the fears the procedure aroused in many people.

The use of the vaccine derived from observations that people who worked with cows, like milkmaids and got "cowpox" never got smallpox. 

Jenner was not the first to use the procedure. A farmer, Benjamin Jesty, pictured below, employed it about twenty years before.

But Jenner (below) was the first to publicize it and get credit, a knighthood, and a ton of money from Parliament.

Before the use of "vaccine" an immunization using actual smallpox pus from human cases had been in use, in some places for centuries. Inoculation, or variolation, as it was called, was intended to induce a mild case of the disease and lifelong immunity. It was not always mild. It had a mortality rate of about 1% inoculated and it sometimes left ugly scars. Image below compares inoculation and vaccination effects on arms.

The natural disease, however, often killed 20% or more of the infected, which explains the attraction of inoculation, especially during epidemics. The "ad" below for vaccination shows a scar-free arm.

Vaccination was much safer than inoculation, but it did not provide lifelong immunity. Once that was understood, periodic re-vaccination became standard in the later 19th century. Image below shows people being vaccinated in the US, ca. 1870s.

Public resistance to vaccination remained high for a long time. By 1979, however, vaccination for smallpox had eradicated one of the greatest killer diseases known to mankind. Its success had also led to the development of many other "vaccines."

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