Vaccine origins, science behind how vaccines work and how outbreaks of diseases can occur if vaccination levels drop too low. Vaccines are arguably the most successful medical interventions in human history saving millions of lives annually and contributed significantly to the elimination of one of the world’s most deadly diseases, smallpox. In this episode we cover the origins of vaccination and the science behind how vaccines work. We also discuss how common misgivings about vaccination can lead to dangerous outbreaks of infectious disease. Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales; http://creativecommons.org/licenses/by-nc-sa/2.0/uk/