An Ebola vaccine known as VSV-EBOV, developed by the Public Health Agency of Canada, has shown 100% efficacy in individuals according to results from an interim analysis published by The Lancet.
“This is an extremely promising development,” said Margaret Chan, M.D., 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.”
An independent body of international experts, the Data and Safety Monitoring Board, conducted the review of the study so far.
Based on the initial results, the Guinean national regulatory authority and ethics review committee have approved continuation of the trial to acquire conclusive evidence for the vaccine’s capacity to protect populations through what is called “herd immunity.”
“The ‘ring’ vaccination method adopted for the vaccine trial is based on the smallpox eradication strategy. The premise is that by vaccinating all people who have come into contact with an infected person you create a protective ‘ring’ and stop the virus from spreading further. This strategy has helped us to follow the dispersed epidemic in Guinea, and will provide a way to continue this as a public health intervention in trial mode.” said John-Arne Røttingen, Director of the Division of Infectious Disease Control at the Norwegian Institute of Public Health and Chair of the Study Steering Group.
It isn’t just a success in the battle against Ebola, but shows that ongoing awareness of diseases can spur research into faster results.
“This record-breaking work marks a turning point in the history of health R&D,” said Assistant Director-General Marie-Paule Kieny, who leads the Ebola Research and Development effort at WHO. “We now know that the urgency of saving lives can accelerate R&D. We will harness this positive experience to develop a global R&D preparedness framework so that if another major disease outbreak ever happens again, for any disease, the world can act quickly and efficiently to develop and use medical tools and prevent a large-scale tragedy.”
In the study, 4,123 people were randomly assigned to 48 immediate vaccination clusters and 3,528 people were assigned to 42 delayed vaccination (21 days or later) clusters.
Of the 48 immediate vaccination clusters, 2,014 (49%) were vaccinated. Of the 42 delayed vaccination clusters, 1,498 (42%) were vaccinated.
After 10 days or more, no Ebola virus RNA was found occurred in the immediately vaccinated participants compared with 16 cases in 7 delayed vaccination clusters giving an estimated vaccine efficacy of 100%.
The estimated efficacy of the vaccine in eligible people (vaccinated and unvaccinated) is 75.1%, and the estimated efficacy in all 90 clusters is 76.3%. This means that there is a lower chance of catching Ebola virus when surrounded by vaccinated people, which is the basis of herd immunity.
