Smallpox: Technical Background on the Disease and Its Potential Role in Terrorism [Updated January 10, 2003] [open pdf - 33KB]
From the Summary: "Smallpox, which kills approximately 30% of its victims, is estimated to have killed between 300 and 500 million people in the twentieth century before the World Health Organization's successful eradication program. The smallpox vaccine is effective at preventing smallpox but has a higher complication rate than any other currently used vaccine. The terrorist attacks of 2001 have increased fears that smallpox might be used as a weapon of terror. Smallpox has several properties that might make it desirable by terrorists, such as contagiousness and high lethality. These factors and its limited availability also make it difficult for a terrorist to use. Most experts agree that it is very unlikely that smallpox will be used as a weapon, but the high consequences of a successful attack have prompted exploration of methods to counter this threat. Also see CRS [Congressional Research Service] Report RL31694 'Smallpox Vaccine Stockpile and Vaccination Policy' and CRS Report RL31368, 'Preventing Proliferation of Biological Weapons: U.S. Assistance to the Former Soviet States.' This report will be updated as warranted."
CRS Report for Congress, RS21288