Researchers have found that many vaccine adjuvants work by eliciting early, innate immune responses. Since the mid-1990s, scientists have made many new discoveries in the field of innate immunity. These advances have led to identification of many promising adjuvant candidates.
In some instances, scientists have identified the molecules on innate immune cells that adjuvants target, and these interactions can account for the adjuvant activity. However, the molecular mechanisms underlying the activity of many adjuvants are only partially understood. Researchers agree that adjuvants help direct particular types of immune responses, recruit specific populations of immune cells, and play a role in the ability of innate immune cells to shape the adaptive immune response (T and B cells). Adjuvants function through a range of mechanisms. Increasing understanding of how adjuvants work to stimulate particular immune responses will play an important role in the development of new and improved vaccines.