Contemporary vaccination is rooted in centuries of scientific discovery. Some scholars believe that as far back as 1000 CE, Chinese Taoists used variolation (or inoculation) to control the spread of disease. In 1796, Edward Jenner developed a smallpox vaccine that ranks as one of the most important scientific breakthroughs of all time. This book explains how Jenner made his discovery based on the achievements of those who came before him, how vaccination works, and the many ways that vaccines continue to shape science (and generate controversy) today.