1796 in may, jenner inoculated an 8-year-old boy with a substance extracted from cowpox pustules on the fingers of dairy workers. Sure enough, the boy got vaccinia, but he soon recovered. A few weeks later, Jenna vaccinated him against smallpox again. As he expected, the boy showed no signs of smallpox.

After further investigation, Jenner wrote the results into a small book and published it in 1798. After that, he wrote five articles about vaccinia, and he devoted all his time to the spread and promotion of this technology. The application of vaccinia soon spread in Britain, and soon the British army and navy stipulated that vaccination was necessary. Finally, vaccination has been adopted in most parts of the world.