text: A vaccine is a type of medicine that trains the body’s immune system so that it can fight a disease it has not come into contact with before. Vaccines are designed to prevent disease, rather than treat a disease once you have caught it.
  To understand how vaccines work, it helps to look first at how the immune system works, because vaccines harness the natural activity of your immune system. This short animation explains how vaccines enable the body to make the right sort of antibodies to fight a particular disease. Click here to download the script of the animation.