The Variola virus, of the Poxviridae family, was the agent responsible for smallpox, a disease that had a great importance in human history and that was also at the origin of the development of vaccination as a prevention tool.

The World Health Organization officially declared this disease eradicated in 1980. Therefore compulsory vaccination in Italy was suspended in 1977 and definitively abrogated in 1981. Virus reserves, for study reasons, are officially maintained only in two laboratories in tight security conditions: one in the United States and one in Russia.