The first and only human disease to be eradicated through vaccination. Caused by the variola virus, now kept only in secure laboratories for research.
Smallpox, caused by the variola virus, has plagued humanity for thousands of years. It is estimated to have killed 300-500 million people in the 20th century alone. In 1980, the WHO declared smallpox eradicated—the first and only human disease to be eliminated through deliberate human effort (WHO, 1980).
The last known naturally occurring case was in Somalia in 1977. Two secure WHO reference laboratories (CDC in Atlanta and VECTOR in Russia) retain virus stocks for ongoing research. The question of whether to destroy remaining stocks has been debated for years.