Adjuvants
Adjuvant: An immunological agent that increases the antigenic response.
Adjuvants are widely used in vaccines, but how and why they work is not well understood. A typical adjuvant would be an aluminum compound that causes an increase in the antibody and other immune components after injection.
Vaccine proponents hope that the response is specific to the type of vaccine being given, as though the body can tell what was injected along side the adjuvant as opposed to what also happens to be floating around in the body at the injection site or eventually the bloodstream, but this has not been well researched. Some suspect that the response is simply a reaction to the adjuvant itself, setting up auto-immune type of problems when that adjuvant lodges itself into a body organ.