Destruction of variola virus: memorandum from a WHO meeting.

This Memorandum discusses the fate of variola virus stocks which have been kept in two WHO Collaborating Centres, as well as cloned DNA fragments of variola virus genome, smallpox vaccine, and seed vaccinia virus for the production of this vaccine. General and specific recommendations are given concerning destruction of variola virus; storage, distribution and handling of cloned DNA fragments of variola virus genome; and about stocks of smallpox vaccine.