There are several methods of making vaccines. One method uses an inactivated, or killed, organism as the immune system stimulant. The body is exposed to the entire microorganism, but since it has been killed, it cannot make you sick. An example of this type of vaccine is the injectable polio vaccine.
Another method uses a weakened, or attenuated, virus as the stimulant. In this case, the organism has been carefully weakened but not killed. Again, the body sees the entire organism and develops a full immune response to the vaccine. However, the weakened virus can only give you at most a mild version of the disease. Examples of this type of vaccine include measles, mumps, rubella, and chickenpox vaccines as well as the oral polio vaccine.
A third method of making vaccines involves using certain sugars or proteins from the pathogen as the immune system stimulant. This is done in two ways. In some cases, the sugars are linked to another protein in order to boost the immune response. This process is called polysaccharide conjugation. In another process, genetic engineering is used to produce specified proteins that act as the immune system stimulant. These special proteins are called recombinant vaccines. With both these types of vaccines, only parts of the pathogen are present, so it is impossible to get the disease from the vaccine. Examples of these methods include HiB, which is a polysaccharide conjugate vaccine, and hepatitis B, which is a recombinant vaccine.