Early trials of Ebola vaccine show immune responseBMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h1844 (Published 08 April 2015) Cite this as: BMJ 2015;350:h1844
Small, phase I trials in Africa and Europe of an experimental vaccine against Ebola virus disease have shown an immune response in all of the healthy adults vaccinated, preliminary results reported in the New England Journal of Medicine have shown.1
The Zaire variant candidate vaccine rVSV-ZEBOV uses live recombinant vesicular stomatitis virus (rVSV), a livestock disease that generally causes no or only mild illness in humans, to carry DNA from Zaire ebolavirus with the aim of stimulating an immune response.
Researchers carried out three open label phase I trials with the vaccine at various doses and one randomised double blind trial to assess the immunogenicity and safety of the vaccine in 158 healthy adults in Africa and Europe (150 received the vaccine, and eight received placebo).
Results showed that the vaccine generated an immune response in all study participants, confirming its immunogenicity in humans. Response was assessed by measuring levels of antibodies to a glycoprotein expressed on the surface of Zaire ebolavirus. These antibodies were detected in all study participants at all doses of vaccine tested, but higher levels of neutralising antibodies were seen at higher vaccine doses.
None of the study participants had serious vaccine related adverse events. Mild to moderate reactions were common but transient, lasting for a median of one day. Fever occurred in about 35% of vaccines.
Arthritis affecting one to four joints developed in 11 of 51 participants (33%) in one of the European trials, with pain lasting for a median of eight days.
“First results of rapidly implemented, parallel phase 1 studies . . . showed that the rVSV-ZEBOV vaccine is reactogenic but immunogenic at doses ranging from 300 000 to 50 million PFU [plaque forming units] in African and European volunteers, with higher titres of neutralising antibodies at higher doses,” said the study authors, from the VSV Ebola Consortium created by the World Health Organization to initiate phase I trials to enable rapid progression to phase II and III studies in countries affected by Ebola.
The results after a single dose “warrant further evaluation for safety and efficacy,” the research group said. They concluded, “The viral dissemination in skin and joints that was observed in some participants needs to be balanced with the possible benefit offered by this vaccine in the potential control of outbreaks of Ebola virus disease.”
Cite this as: BMJ 2015;350:h1844