For thousands of years smallpox was the worst virus in the world. It killed more people than any other disease - perhaps as many as half a billion in the 20th Century alone.But then, following a concerted global effort of vaccination, we wiped it out - the only disease threatening humans to have been fully eradicated.Will tells Rod how this happened!The Wholesome Show is Dr Rod Lamberts and Dr Will Grant, proudly brought to you by The Australian National Centre for the Public Awareness of Science!See omnystudio.com/listener for privacy information.