An experimental Ebola vaccine produced immune responses in all 20 patients it was tested on.
The candidate vaccine, developed by NIH's National Institute of Allergy and Infectious Diseases (NIAID) and GlaxoSmithKline (GSK), showed promise in a Phase 1 clinical trial.
"The unprecedented scale of the current Ebola outbreak in West Africa has intensified efforts to develop safe and effective vaccines, which may play a role in bringing this epidemic to an end and undoubtedly will be critically important in preventing future large outbreaks," said NIAID Director Anthony S. Fauci, M.D. "Based on these positive results from the first human trial of this candidate vaccine, we are continuing our accelerated plan for larger trials to determine if the vaccine is efficacious in preventing Ebola infection."
The vaccine contains segments of Ebola virus genetic material from two species and is delivered by a carrier virus that causes a common cold in monkeys but no symptoms in humans.
To test the new vaccine the researchers enrolled participants between the ages of 18 and 50; 10 of these patients received an intramuscular injection of the vaccine at a lower dose and the other 10 received it at a higher dose. At two weeks and four weeks following the vaccination; the researchers noticed all 20 patients produced anti-Ebola antibodies by the four-week mark, but these levels were higher in those who had received the higher dose. No serious adverse effects were observed in any of the participants.
The vaccine was found to induce a T-cell response, such as the production of CD8 T cells, in two of the participants that received the lower dose and seven that recived the higher.
"We know from previous studies in non-human primates that CD8 T cells played a crucial role in protecting animals that had been vaccinated with this NIAID/GSK vaccine and then exposed to otherwise lethal amounts of Ebola virus," said Julie E. Ledgerwood, a VRC researcher and the trial's principal investigator. "The size and quality of the CD8 T cell response we saw in this trial are similar to that observed in non-human primates vaccinated with the candidate vaccine."
The findings were published in a recent edition of the New England Journal of Medicine.
