ABSTRACT
Introduction: The Ebola virus (EBOV) disease epidemic during 2014–16 in West Africa has accelerated the clinical development of several vaccine candidates that have demonstrated efficacy in the gold standard nonhuman primate (NHP) model, namely cynomolgus macaques.
Areas covered: This review discusses the pre-clinical research and if available, clinical evaluation of the currently available EBOV vaccine candidates, while emphasizing the translatability of pre-clinical data generated in the NHP model to clinical data in humans.
Expert opinion: Despite the existence of many successful EBOV vaccine candidates in the pre-clinical stages, only two platforms became the focus of Phase 2/3 efficacy trials in Liberia, Sierra Leone, and Guinea near the peak of the epidemic: the Vesicular stomatitis virus (VSV)-vectored vaccine and the chimpanzee adenovirus type 3 (ChAd3)-vectored vaccine. The results of three distinct clinical trials involving these candidates may soon pave the way for a licensed, safe and efficacious EBOV vaccine to help combat future epidemics.
Declaration of Interest
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
Article highlights
An abundance of vaccine candidates have performed well with pre-clinical testing in NHPs.
Some candidates have hurdles to overcome before advancement to clinical trials due to safety reasons (RABV and EBOVΔVP30, and at one point live, replicating recombinant viruses such as VSV).
Phase 1 trials have demonstrated the safety and immunogenicity of Ad5-EBOV, ChAd3-EBO Z, and VSVΔG/EBOVGP vaccines.
Clinical trials to evaluate the efficacy of ChAd3-EBO Z, VSVΔG/EBOVGP, and the Ad26.ZEBOV and MVA-BN-Filo heterologous prime-boost regimen were initiated in affected areas of West Africa, most were unable to elucidate efficacy due to the decline of the epidemic by late 2015.
Only VSVΔG/EBOVGP has demonstrated preliminary efficacy in a clinical trial setting, demonstrating 100% efficacy by the end of 2015.
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