Adjuvants: present regulatory challenges.

Research on new adjuvants and delivery systems has expanded dramatically in the last decade. New generation vaccines, based on recombinant proteins, synthetics, and conjugated antigens have emerged but they have limitations because of their poor immunogenic properties, and therefore more cooperative adjuvants for the promotion of the immune response are required. Different molecules have been screened for their ability to enhance the immune response to vaccine antigens, e.g. liposomes, protein cochleate formulations, ISCOMs and cytokines, to name the few. However, most of the vaccines that are currently licensed use aluminum salts or calcium phosphate.