Figure 3. Ebola vaccine development pathway using the animal rule.

Early vaccine candidates are optimized for immune potency in small animal models. Selected candidates are evaluated further in an animal model that adequately represents infection in humans (cynomolgus macaques) to establish an immune correlate of vaccine efficacy, and a pivotal animal study is performed to bridge the immune correlate between macaque efficacy studies and human Phase II clinical trials. Data from Phase III animal studies and expanded Phase II human studies are compiled for regulatory review and vaccine licensing.