“This is Guinea’s gift to West Africa and the world,” said Dr Sakoba Keita, Guinea’s national coordinator for the Ebola response. “The thousands of volunteers from Conakry and other areas of Lower Guinea, but also the many Guinean doctors, data managers and community mobilizers have contributed to finding a line of defense against a terrible disease.”
What Dr. Keita is referring to is the Phase 3 trials results in Guinea of the Merck, Sharp & Dohme investigational Ebola vaccine, rVSV-ZEBOV.
Merck reported the preliminary conclusions from this study, which is continuing, were published on-line today in The Lancet. The authors report that vaccine efficacy was 100 percent (95% confidence interval: 74.7 – 100%; p=0.0036) following vaccination with a single dose of the rVSV-ZEBOV vaccine. It appeared that all vaccinated individuals were protected against Ebola virus infection within 6 to 10 days of vaccination.
To date, more than 4,000 participants have received the vaccine in this innovative trial, called “Ebola ça suffit” or “Ebola, that’s enough.” The trial was conducted by a team that included researchers from the World Health Organization (WHO), the Norwegian Institute of Public Health, the Health Ministry of Guinea and Médecins sans Frontières, among others.
“This is an extremely promising development,” said Dr Margaret Chan, Director-General of the World Health Organization. “The credit goes to the Guinean Government, the people living in the communities and our partners in this project. An effective vaccine will be another very important tool for both current and future Ebola outbreaks.”
The rVSV-ZEBOV vaccine was initially engineered with support from the Public Health Agency of Canada and was licensed to NewLink Genetics Corporation. To make the vaccine, the vesicular stomatitis virus was weakened by removing one of its genes, which was then replaced with a single Ebola virus gene that cannot cause disease by itself.
Vaccinated individuals have been shown to develop antibodies against the Ebola virus, which could help protect against future infection. The significance and durability of this immune response have not been determined.
Médecins sans Frontières (Doctors without Borders) weighed in on the study results saying that frontline Ebola workers need to be vaccinated.
MSF Medical Director, Bertrand Draguez said, “In parallel with the ring vaccination, we are also conducting a trial of the same vaccine on frontline workers.
“These people have worked tirelessly and put their lives at risk every day to take care of sick people. If the vaccine is effective, then we are already protecting them from the virus. With such high efficacy, all affected countries should immediately start and multiply ring vaccinations to break chains of transmission and vaccinate all frontline workers to protect them.”