The first clinical trial of an Ebola vaccine is expected to begin in the Democratic Republic of Congo by the end of October, World Health Organization experts said Tuesday.
The DR Congo's worst-ever Ebola outbreak has passed the 9,000-case mark, with the number of deaths exceeding 4,000.
Among the many challenges facing the response is the lack of any approved vaccines or treatments for the Bundibugyo species of Ebola behind the outbreak.
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"We have got strong reassurances that... it should be starting before the end of this month," said Anthony Scott, chair of the WHO's Strategic Advisory Group of Experts on Immunisation (SAGE).
The group said insights that Ervebo might offer cross-protection against Bundibugyo were no match for evidence from standardised vaccine trials.
The so-called Tumaini trial in the DRC -- a single trial framework that can test the efficiency of multiple vaccines -- should also eventually incorporate two Bundibugyo-specific candidate vaccines, which are moving through earlier-stage, smaller-scale clinical trials.
One is a ChAdOx1 adenoviral vector jab being developed by the University of Oxford; the other, by the US-based Moderna group, uses mRNA technology.
WHO says Congo Ebola outbreak spreads to two new health zones Need for data The Tumaini trial "will generate urgently-needed data on the efficacy of Ervebo against Bundibugyo virus disease, and will help formulate the policy decisions we need", Scott told a press conference.
"In addition, we welcome the accelerated development of vaccines that are specifically targeting Bundibugyo.
"They're both progressing rapidly through early clinical development." SAGE said it was deeply concerned about the ongoing challenges in controlling the Ebola outbreak.
"The key elements here are insecurity and population displacement, and they're hindering access to care, disrupting surveillance, and delaying critical research, including, from our perspective, research on vaccine trials," said Scott.
Kate O'Brien, director of the WHO's immunisation department, said a WHO technical advisory group would be meeting to review evidence from the small-scale trials of the Oxford and Moderna candidate vaccines.
She suggested the Oxford jab could drop into the broader Tumaini trial fairly swiftly -- as doses are ready to roll -- if the safety and the immunogenicity data from the first trial is "positive and reassuring".
Therefore "everything is lined up for at least two products to be moving quickly", she said.
The medical charity Doctors Without Borders is conducting a data-gathering study -- not a full clinical trial -- of Ervebo's effectiveness in frontline health workers in DRC provinces hard-hit by the Bundibugyo outbreak, with the jab being offered to volunteers as an interim measure.
