"A killer virus … an all-powerful Empress … an encounter cloaked in secrecy. Within living memory, smallpox was a dreaded disease. Over human history it has killed untold millions. Back in the eighteenth century, as epidemics swept Europe, the first rumours emerged of an effective treatment: a mysterious method called inoculation. But a key problem remained: convincing people to accept the preventative remedy, the forerunner of vaccination. Arguments...