- Underscoring the multitude of practical difficulties facing Ebola vaccine trial conductors, phase III vaccine studies are being complicated by the fact that just 30 cases of Ebola were reported in West Africa last week, leaving investigators too few study subjects.
- The three-country hotspot for Ebola included Guinea, Liberia and Sierra Leone; however, the epidemic is waning rapidly. The best hope is a clinical trial that is currently underway in Guinea.
- In the worst case scenario, even if large clinical trials in West Africa are not able to produce efficacy results based on well-powered studies, companies can still submit to regulators by using efficacy data from non-human primates.
Of course, it's a good problem to have. The goal of the comprehensive, multi-country, all-hands-on-deck strategy that finally contained the Ebola epidemic has made it hard for companies that are developing Ebola vaccines. However, at least one study is continuing uninterrupted. Investigators are testing a vaccine co-developed by NewLink Genetics and Merck, using a "ring of immunity" approach. So far, investigators have immunized subjects in seven of 100 allocated rings.
The reality is that the Ebola epidemic could easily come back, even if it's not for a period of months or years. The World Health Organization is exhorting vaccine developers to continue R&D efforts, with the future in mind.