The vaccine used in this trial—rVSV-ZEBOV, a recombinant, live, attenuated, vesicular stomatitis virus vaccine expressing the surface glycoprotein of Zaire Ebola virus—had been developed by the Public Health Agency of Canada in 2003, licensed in 2010 to a small biotech company, NewLink Genetics of Ames Iowa, which licensed it to Merck, of Kenilworth, New Jersey. When Merck stepped in, in November, 2014, the vaccine had never been put into humans, although preclinical studies in non-human primates gave promising results. To make up for lost time—by now the epidemic was well underway—eight separate phase 1 trials were done simultaneously by various groups and in various places around the globe, and from those trials, the vaccine was deemed safe. Speaking at a meeting on medical countermeasures and preparedness, convened by the US Institute of Medicine last March, Mark Feinberg, Merck Vaccines' vice president, said “It was the fastest Merck has ever done anything.”
The ring-vaccination trial of rVSV-ZEBOV, called “Ebola ça Suffit” (“Ebola, that is enough”), began in April 2015, coordinated by Merck and carried out by the World Health Organization along with health agencies from Canada, Norway and South Africa, and academic groups hailing from as many continents. At this point, the number of cases of Ebola had been dropping, and the prospect of doing a placebo-controlled trial was deemed not only unethical but impossible. Instead, an open label, cluster-randomized, ring-vaccination trial was undertaken in Guinea, the only affected area still reporting cases. The primary negative outcome was to be laboratory-confirmed Ebola at least ten days after randomization, the timing reflective of what is known about the virus's incubation period.
This is a preview of subscription content, access via your institution