The West African Ebola virus outbreak between 2013 and 2016 was the worst in history, resulting in more than 28,000 cases and 11,000 deaths. Fortunately, researchers at the National Institutes of Health (NIH) had been working for many years to make a vaccine to prevent it. In the Jan. 26, 2017, issue of the New England Journal of Medicine, investigators at the Walter Reed Army Institute of Research and National Institutes of Health Clinical Center published the results of a phase 1 study of this Ebola vaccine (Regules JA, Beigel JH, Paolino KM, et. al. A Recombinant Vesicular Stomatitis Ebola Vaccine. N Engl J Med 2017 Jan 26;376(4):330-41).
Researchers at NIH made the Ebola vaccine by taking the gene that codes for the Zaire strain of Ebola virus surface glycoprotein and inserting it into a replication competent strain of vesicular stomatitis virus (VSV). VSV infects insects, horses, pigs and cattle, and can rarely cause a flu-like illness in people. The phase 1 trial of the recombinant vaccine was designed to determine the optimal dose necessary to induce a protective immune response. A total of 39 adults were inoculated with either 3 million, 20 million, or 100 million plaque-forming units (PFU) of the VSV-Ebola glycoprotein vaccine. Excellent immune responses were detected in all recipients at both the 20 million and 100 million PFU doses. The most common side effects following vaccination were injection-site pain, fatigue, myalgia and headache. Transient viremia of the VSV-Ebola recombinant was detected in all vaccinees after dose 1. At one site, a second dose of the vaccine was given, resulting in a booster response.
On the basis of these encouraging results, phase 3 trials of the 20 million PFU dose of the VSV-Ebola glycoprotein vaccine will soon be performed in Liberia and Sierra Leone.