a method of testing the sensitivity of an individual to a hormone, allergen, or other substance by administering a sample. ... To challenge the person's sensitivity to a particular antigen, a small amount may be injected to determine whether the immune system will react by producing appropriate antibodies.
In principle, demonstration of efficacy shall be undertaken under well controlled laboratory conditions by challenge after administration of the immunological veterinary medicinal product to the target animal under the recommended conditions of use. In so far as possible, the conditions under which the challenge is carried out shall mimic the natural conditions for infection, for example with regard to the amount of challenge organism and the route of administration of the challenge.
