Jonas Salk's polio vaccine has taken on an almost legendary quality as a medical miracle, for it largely eradicated one of the most feared diseases of the 20th century. But the story of the vaccine has a dark side, one that has never been fully told before... Between 1954 and 1963, close to 98 million Americans received polio vaccinations contaminated with a carcinogenic monkey virus, now known as SV40. A concerted government effort downplayed the incident, and it was generally accepted that although oncogenic to laboratory animals, SV40 was harmless to humans. But now SV40 in showing up in human cancers, and prominent researchers are demanding a serious public health response to this forgotten polio vaccine contaminant. A gripping medical detective story, The Virus and the Vaccine raises major questions about vaccine policy.