Vaccinations prepare the body's immune system to fight invasions of a specific pathogen by introducing a small amount of a weakened or inactivated form of that pathogen into the body. This prompts the immune system to produce antibodies and activate immune cells that can recognize and fight the pathogen if it enters the body again in the future. This process is known as "immunization". By receiving a vaccination, the body is able to develop a memory of the pathogen and can respond more efficiently to an actual infection, allowing the immune system to quickly and effectively fight off the pathogen and prevent the person from getting sick.
