A senior official from the global vaccine coalition CEPI warned on Thursday that the number of Ebola cases currently recorded in the eastern Democratic Republic of Congo likely reflects only the visible portion of a much larger outbreak, and cautioned that developing a safe, effective vaccine within a compressed timeframe will be challenging.
The outbreak in eastern DRC currently encompasses around 600 suspected cases and more than 130 suspected deaths. The World Health Organization has declared the situation a public health emergency of international concern.
"I have described this outbreak as being like an iceberg, we’ve seen the top of the iceberg, the top, as we get closer to it, is pretty large," Jane Halton, chair of the Board of the Coalition for Epidemic Preparedness Innovations, said at a briefing held by the ACANU press club in Geneva.
Halton emphasized that the officially reported figures likely understate the true burden of the outbreak. "We are now into the many hundreds of cases and hundreds of deaths, but the truth of the matter is that real numbers are much bigger than that," she said.
CEPI, which provides funding for new vaccine development and is evaluating potential Ebola candidates, has established an objective of having a safe, effective vaccine for major outbreaks within 100 days. Earlier in the outbreak commentary the target timeline had also been referred to as around three months.
Asked whether that accelerated target could be met in this situation, Halton responded, "Possibly, it’s a big lift," while noting a clear improvement in response capability over recent years. "I can guarantee you that we will be in a position to respond faster than we would have been five years ago." She did not specify a firm timetable.
The strain involved in this outbreak is Bundibugyo. Unlike the more common Zaire strain of Ebola, for which there are established research efforts, there are no approved virus-specific therapeutics or vaccines for the Bundibugyo strain. The Bundibugyo strain has previously been observed to be less lethal.
Halton said antibody collection activities had been under way before the outbreak emerged, and that a vaccine candidate targeting the Bundibugyo strain had been planned as the "next cab off the rank" for development prior to the current event. She described the timing of the outbreak relative to that work as "regrettable" and "a very difficult position."
With several early-stage vaccine candidates under consideration, CEPI is working to accelerate preclinical safety testing so a trial could be run during the ongoing outbreak, Halton added. Any clinical testing would depend on securing informed consent from affected local communities.
Context and implications
The remarks underline both the difficulty of assessing the full extent of an outbreak in real time and the practical hurdles of moving candidate vaccines from laboratory stages into field trials quickly. CEPI's stated rapid-response objective reflects an intention to shorten the interval between identification of an outbreak and availability of an effective countermeasure, but officials acknowledge significant operational challenges remain.