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Science in the News

Ebola Prevention Update: Results of an Ebola Virus Vaccine Trial Published

August 06, 2015

The Lancet has published the first results from a phase 3 cluster randomized trial, conducted in Guinea, of an Ebola virus vaccine.1 The vaccine is a replication-competent recombinant vesicular stomatitis virus (rVSV)-based vaccine, expressing a Zaire Ebolavirus (ZEBOV) glycoprotein as previously described.2 Results of a previous phase 1 trial indicated that this vaccine was safe.3

The data from the phase 3 trial are interim results from 4/1/15 to 7/20/15, and provide estimates of vaccine effectiveness. Within a few days of notification of a confirmed case of Ebola, a cluster of all contacts and contacts of contacts were randomized to immediate or delayed vaccination. This initial report suggests that immediate vaccination with a single dose of the vaccine may be highly protective and that protection was established quickly. Although not statistically significant, the data are suggestive that the rate of Ebola infection was lower within a vaccinated cluster even among those who were unvaccinated.

This study adds the first experimental evidence about a preventive intervention for those most at risk of Ebola virus infection.


1. Henao-Restrepo AM, Longini IM, Egger M, et al. Efficacy and effectiveness of an rVSV-vectored vaccine expressing Ebola surface glycoprotein: interim results from the Guinea ring vaccination cluster-randomised trial. Lancet 2015. Accessed August 5, 2015.
2. Agnandji ST, Huttner A, Zinser ME, et al. Phase 1 Trials of rVSV Ebola Vaccine in Africa and Europe - Preliminary Report. N Engl J Med 2015. Accessed August 5, 2015.
3. Regules JA, Beigel JH, Paolino KM, et al. A Recombinant Vesicular Stomatitis Virus Ebola Vaccine - Preliminary Report. N Engl J Med 2015. Accessed August 5, 2015.

About Science in the News

Science in the News is a service by the American Dental Association (ADA) to its members to present current information about science topics in the news. The ADA is a professional association of dentists committed to the public's oral health, ethics, science and professional advancement; leading a unified profession through initiatives in advocacy, education, research and the development of standards. As a science-based organization, the ADA's evaluation of the scientific evidence may change as more information becomes available. Your thoughts would be greatly appreciated.

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