In medicine, a vaccination is a preventive measure taken against infectious diseases. It seeks to protect the vaccinated person from a certain disease, for example tetanus or hepatitis. When you are vaccinated, you are given the pathogen which actually makes you sick, just in a very small dose.  The body's protective reaction is to form antibodies against the pathogens. The body then recognizes their outer appearance, i.e. its molecular surface structure. In this film, we will learn how exactly vaccinations make us immune. At the end of the film you will find a glossary with a summary of the contents.