Vaccinations are also called vaccines and immunizations. They’re medical treatments that teach your immune system to recognize and protect you against germs (bacteria and viruses) that make you sick. Vaccinations are given as an injection, liquid, pill, or nasal spray. Vaccinations contain weakened or dead germs or specific proteins unique to a germ. When administered into your body, your immune system recognizes the germ as a foreign agent and creates antibodies. If you come in contact with the germ at another time, your immune system recognizes the germ and activates the antibodies needed to kill it, potentially preventing you from getting sick at all or at least from developing severe symptoms. This is how your immune system works when you get sick from real viruses like chickenpox. However, with the vaccine, you never get sick because the vaccine has given you the benefits of immunity.