Smallpox virus is in a class of its own as the world’s worst killer virus. It first infected humans at least 5,000 years ago and killed around 300 million in the 20th century alone. The virus killed up to 30 per cent of those it infected, scarring and blinding many of the survivors. But after centuries of devastation, smallpox virus was finally eliminated from the wild in 1980. The fight to prevent and eliminate smallpox is recounted in Chapter 9