Ebola: Lessons on Vaccine Development

The West African Ebola virus (EBOV) epidemic has fast-tracked countermeasures for this rare, emerging zoonotic pathogen. Until 2013-2014, most EBOV vaccine candidates were stalled between the preclinical and clinical milestones on the path to licensure, because of funding problems, lack of interest from pharmaceutical companies, and competing priorities in public health. The unprecedented and devastating epidemic propelled vaccine candidates toward clinical trials that were initiated near the end of the active response to the outbreak. Those trials did not have a major impact on the epidemic but provided invaluable data on vaccine safety, immunogenicity, and, to a limited degree, even efficacy in humans. There are plenty of lessons to learn from these trials, some of which are addressed in this review. Better preparation is essential to executing an effective response to EBOV in the future; yet, the first indications of waning interest are already noticeable.