[Incidents in repositories of smallpox virus laboratories and review]

Reposition of variola virus in some laboratories in the United Kingdom led to serious incidents before the announcement by WHO of the Global Eradication of Smallpox in 1980. These three incidents resulted in 78 people recorded as infected with smallpox, among whom 3 died, and very many more were misdiagnosed at the time as suffering from chickenpox. Therefore WHO discussed the problems and decided to reduce gradually the number of repositories of variola virus in laboratories world-wide from previously unknown numbers to two. However, in the event of a sudden outbreak of a new mutated smallpox virus, publications on that ancient but almost forgotten prophylactic practice of variolation could be of considerable contingency value.