Why, which, how, who, when? A personal view of smallpox vaccination for the 2000s.

The uncertainty about the extent of proliferation of smallpox virus holdings since the early 1990s, and particularly whether terrorist groups or so-called rogue states might now hold the virus, confronts potential target countries with a continuing dilemma. An increasingly large majority of their populations have never been vaccinated, and those who have been vaccinated may have become susceptible to smallpox again. Yet recent attempts by the United States and other governments to persuade large numbers of key personnel and others to accept vaccination have at least partially failed and a different long-term strategy is needed. This strategy should be based on surveillance of rash illnesses, improved public education, more refined contingency planning and a new approach to smallpox vaccination. The last should if possible be based on cell-grown, less reactogenic vaccines, even though it may be some years before these can become available. Meanwhile this article examines other expedients including the use of existing lymph vaccines.