Smallpox
was an infectious disease caused by one of two viruses, Variola
major and Variola minor. It is estimated that smallpox was responsible for 300-500 million deaths
worldwide. The last naturally occurring case was diagnosed in October 1977 and the World Health
Organization (WHO) certified the global eradication (elimination) of the disease in 1980. This was
accomplished by the creation of a vaccine by Edward Jenner in 1796. This vaccine was the first successful
vaccine to be developed.
What part of the Chain of Infection was broken by the development of the Smallpox vaccine?