On May 8, 1980, the World Health Organization declared the end of the threat of smallpox. This deadly disease had finally been eradicated through the development of the smallpox vaccine. It sure took a long time, though.

The beginning of the end of smallpox came in 1796 when Edward Jenner not only developed a smallpox vaccine but invented the idea of vaccines in general. It was well known at the time that people who had survived a bout with smallpox never got the disease again, and so some people tried to get themselves protected by catching a “mild” case of smallpox. This usually ended badly. 

Jenner got to thinking, though, and wondered if there might be a way to mimic the effects of a mild case of smallpox using cows. Specifically, he injected people with the blood serum of cows that had cowpox. Cowpox was a bovine version of smallpox, and Jenner hoped that exposure to it would protect against smallpox without actually making people sick with smallpox. His guess proved to be correct. With this new vaccine in hand, Jenner started dreaming of completely wiping the disease off of the face of the Earth. Little did he know it would take almost 200 more years for his dream to finally come true.

At first, people didn’t trust Jenner’s vaccine. Not many people used it, and scientists and charlatans everywhere kept promoting different ideas for treating the disease, hoping to find something better. One popular yet utterly ineffective remedy involved shining red light on smallpox sufferers. Despite its complete lack of effectiveness, it took a surprisingly long time for it to fall out of favor. 

Even when people started coming around to the idea of the vaccine, it was difficult to store, because it needed to be stored at cool temperatures, and refrigeration hadn’t been invented yet. However, a new storage method was discovered, and the use of the vaccine began to spread more rapidly. In 1966, several nations from around the world declared their intention to make Jenner’s dream come true and, by 1980, they’d succeeded.