The Lancet published that preliminary testing of the Guinea Phase III efficacy vaccine trial has proven that VSV-EBOV (Merck, Sharp & Dohme) is extremely effective against Ebola. The Data and Safety Monitoring Board conducted the review and concluded that trial testing should continue.
Up to this point, the vaccine has shown 100% efficacy in individuals. However, the Guinean national regulatory authority wants to see more conclusive evidence that the vaccine can protect large populations through, “herd immunity.” In which, the vaccine would be a form of indirect protection from infectious disease when the majority of the population has become immune to an infection, in that, it would provide certain protection for non-immune individuals.
The Guinea vaccination trial began in late March of 2015, evaluating the efficacy, effectiveness and safety of a single dose of the VSV-EBOV vaccine in affected communities. The vaccine trial is actually based on the smallpox eradication strategy – using the ‘ring’ vaccination method. The idea behind this method is that by vaccinating every person that has come into contact with an infected individual, a protective ring will form and stop the disease from spreading further.
To this date, over 4,000 individuals that were in close contact of 100 Ebola patients such as family members, neighbors, and co-workers have participated in the trial. On July 26, the trial stopped randomization so that all people that were at risk could receive the vaccine immediately and minimize the necessary time to gather more conclusive evidence. Now this has stopped and 50 % of the rings have been vaccinated 3 weeks after the identification of an infected individual to have a comparison with the rings that were vaccinated immediately. The trial will also include new evidence of the vaccine’s safety for 13 to 17-year olds and possibly 6 to 12-year-old children.
“In parallel with the ring vaccination, we are also conducting a trial of the same vaccine on frontline workers,” said Bertrand Draguez, Medical Director at Médecins sans Frontières. “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.”
Dr. Margaret Chan, the Director of the World Health Organization gives credit to the Guinean Government, peopling living in the communities, and their other partners in the project. Dr. Sakoba Keita, Guinea’s national coordinator for the Ebola response sees the vaccine as Guinea’s gift to West Africa and the word. He acknowledges thousands of volunteers from across the country comprising of doctors, data managers and community mobilizers for contributing to the success of the vaccine so far.