Prospects for the development of new vaccine adjuvants

This review focuses on the impact of various new adjuvant formulations on the efficacy of existing and new human vaccines. Despite major advances in our understanding of immunology and vaccine adjuvants, existing and even new prophylactic vaccines seem likely to maintain their dependence upon aluminium salts for the foreseeable future. Additional immunomodulators may be included in these formulations to improve efficacy. A number of immunotherapeutic cancer vaccines appear likely to be registered soon and these will be dependent for efficacy upon new adjuvant formulations. The most useful to date have been the saponins e.g. QS-21, detox-B and Mycobacterial cells (either live as BCG, or killed). Vaccines to treat chronic infections will doubtless benefit from these developments. Adjuvant formulations and technologies exist to permit development of mucosal delivery, needle-free parenteral delivery and single dose vaccines. However, each of these will require intensive development, which will doubtless arrive when demanded by a specific application. Possibilities exist to improve responses in the elderly and to overcome the inhibitory effects of maternal antibodies in neonates. However, considerable work is required to establish the practicality and general utility of new approaches.