Dramatic differences in two boys who were exposed to the same Smallpox source – one was vaccinated, one was not.

Both aged 13 years. Note that while the one on the left is in the fully pustular stage, the one on the right has had only two spots, which have aborted and have already scabbed.

It was one of the deadliest and most contagious diseases known to humankind.

An estimated 300 million people died from smallpox in the 20th century alone. 

A vaccination for smallpox was developed by an English doctor named Edward Jenner in the late 1700s.

In 1980, following an historic global campaign of surveillance and vaccination, the World Health Assembly declared smallpox eradicated – the only infectious disease to achieve this distinction.