EFFICACY OF VACCINES AND NEGATIVE EFFECTS ON EFFICACY

An efficacious control of animal diseases consists of multiple disease control steps, which should optimize the use of vaccines and vaccinat ion programs. Before licensing, the efficacy of vaccines has to be dem onstrated in laboratory trials by challenge and in controlled field tr ials by serological surveillance. After licensing, normally a vaccine is used in a much wider range of animals as tested before licensing. A t that moment, several parameters become evident, which can have a neg ative impact on the efficacy of the vaccine. In cattle for example suc h negative parameters are the general immunity situation acid the stat us of health, seasons and climate, quality of animal housing, disease situation and risk of infection as well as vaccination programs.