Pedantically, as rov states, the Smallpox virus, apparently has been eradicated since about 1980. I say apparently because two sites worldwide are known to have live samples of the virus, the Centers for Disease Control and Prevention in Atlanta, Ga., and the State Research Center of Virology and Biotechnology in Koltsovo, Russia.
A study done about the destiny of these samples was conducted in the last few years as fears of bio-terroism increased, should the sample fall into the wrong hands. Although smallpox has killed an estimate 300 million people over the history of the western world, few, if any people today have immunity to the virus. Worse, even considering that "...smallpox is probably one of the most feared pathogens in history, we understand almost nothing about what it does or how it causes disease. And we have no drugs to treat it..." according to Dr. Grant McFadden, Professor, department of molecular genetics and microbiology, University of Florida, College of Medicine,Professor, Department of Molecular Genetics and Microbiology, University of Florida, College of Medicine.
A paper Dr. McFadden and colleagues have produced is still under peer review...