Ebola vaccine demonstrates promising safety and immunogenicity profiles

Researchers from St George’s, University of London (UK), have reported that an Ebola vaccine – rVSVΔG-ZEBOV-GP – demonstrates an acceptable safety and immunogenicity profile in adults, with consideration of lower doses for pediatric populations.

Professor Sanjeev Krishna (St George’s) commented that: “An unprecedented Ebola outbreak showed how it is possible for academics, non-governmental organizations, industry and funders to work effectively together very quickly in times of medical crisis. The results of the trial show how a vaccine could best be used to tackle this terrible disease effectively.

“We need a system of specialists, medical experts and organizers that maintains vigilance against outbreak diseases like Ebola.

“We should continue to improve ways to make, evaluate and deliver vaccines when they are needed, often in parts of the world lacking in infrastructure for diagnosing infections and providing treatments.”

The study, which was recently published in PLoS Medicine, was a randomized, open-label Phase I trial conducted in Lambaréné, Gabon. The researchers investigated five vaccine doses across 115 adults and a singular dose in 20 adolescents and 20 children. Participants were followed up until 6 months post-injection for safety and immunogenicity measures.

The vaccine contains a non-infectious portion of a gene from the Zaire Ebola virus and was one of two vaccines being examined as a ‘candidate’ option by the WHO to urgently identify a vaccine to combat the Ebola virus outbreak in West Africa.

Researchers discovered that in adults, the 2 × 177 plaque-forming units dose was considered to have an acceptable safety and immunogenicity profile. In pediatric populations, however, the investigators commented that their research supports the consideration of lower doses. This was due to the persistent replication of the rVSVΔG-ZEBOV-GP vaccine observed in children and adolescents with the 2 × 177 plaque-forming unit dose.

In addition to this, the researchers acknowledged that lower vaccine doses should be considered when boosting individuals with pre-existing antibodies to Ebolavirus glycoprotein – a finding that emerged after the vaccine was tested in a country that experienced Ebolavirus outbreaks in the past.

In the study, the researchers concluded that: “Our results and other findings show that this vaccine is safe and immunogenic.” They added that “lower vaccine doses may be needed in pediatric populations as well as for boosting after primary vaccination or naturally acquired immunity.

Sources: Agnandji ST, Fernandes JF, Bache EB et al. Safety and immunogenicity of rVSVΔG-ZEBOV-GP Ebola vaccine in adults and children in Lambaréné, Gabon: a Phase I randomised trial. PLoS Med. 14(10), e1002402 (2017); www.sciencedaily.com/releases/2017/10/171006142352.htm


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