Immunogenicity is the capacity of an antigen to induce an immune response in the body. It is a measure of a given substance's ability to trigger an immune response from the body. A substance with a high immunogenicity can stimulate an immune response in the body, the thought being that with higher immunogenicity, there is a greater chance for the body to produce the desired antibody. It is important in the development of vaccines and other immunotherapies as well as in testing for diseases. Immunogenicity can also be used to evaluate the efficacy of a new vaccine or therapy.