Did you know that the word vaccine comes from the Latin word 'vacca', which means cow? During the late 18th century, smallpox ran roughshod over Europe, killing 1 in 10 people in Britain alone. But strangely, one population seemed less likely to contract the horrible plague: dairy farmers. In 1796, scientist Edward Jenner surmised that the reason these people were immune was because of a prior cowpox, which he found was a weaker strain of the same virus as smallpox. By purposely introducing people to small doses of cowpox, he was able to immunize them to the more serious disease. But have vaccines evolved in the last 200 years?
