According to a commentary, this well conducted randomised trial is an example of how researchers can successfully overcome the multiple issues in study design, operations, and ethics relating to the conduct of clinical studies of interventions against this high-impact infectious disease, which manifests primarily in outbreaks. It notes that the dose-finding component of the trial was important and yielded satisfactory results on safety, but concerns remain about the immunogenicity and the nature and durability of protection when implementing mass vaccination campaigns in future outbreak settings in Africa. It adds that for all Ebola vaccines that have progressed from testing in non-human primate models to clinical trials during the recent outbreak, deeper insights into the long-term innate and adaptive immune responses are needed. The commentators acknowledge that large-scale efficacy clinical trials are impossible to conduct outside of outbreak situations, and the location and scale of the next outbreak are impossible to predict, therefore, sustained investment into research and outbreak preparedness is needed.
Also published in the Lancet are positive interim data from an RCT of rVSV-ZEBOV, a recombinant, replication competent vesicular stomatitis virus-based candidate vaccine expressing a surface glycoprotein of Zaire Ebolavirus which was tested in preventing Ebola virus disease in contacts and contacts of contacts of recently confirmed cases in Guinea.