Invisible Killers - Season 1 Episode 2 -

SMALLPOX tells the story of what many people agree is medical science’s single greatest accomplishment, the complete eradication of the worst disease known to humankind, a scourge responsible for an estimated 500 million deaths in the 20th century alone. However, after its disappearance in 1980, the threat of smallpox never fully abated, it transformed – from a feared and deadly disease into one of the most significant bioterror threats facing humankind.