The Guinean government, with the World Health Organization (WHO), has initiated the very first efficacy trial of an Ebola vaccine this week in an affected community of the Basse-Guinée, one of the areas where most Ebola cases are found in the country. Ring vaccination tests of VSV-EBOV, a lead Ebola vaccine developed by the Public Health Agency of Canada, received an excellent response from the community in a small village in the Coyah prefecture, where the trial team arrived on March 23.
“This landmark operation gives hope to all of us, in Guinea and in the world, that we might soon have an effective public health tool against Ebola, should the vaccine prove to be safe and effective,” says the WHO representative in Guinea, Dr. Jean-Marie Dangou. “The start of ring vaccination clinical testing today in Guinea is therefore one of the most important milestones we have achieved in seeking a modern line of defense against Ebola.”
Trained medical staff, vaccines and other essential equipment were dispatched from Conakry to Coyah to vaccinate contacts of recently infected people who have given consent in a village of the Coyah prefecture. Vaccinations for now will include only adults, who are most at risk of infection, with the exception of pregnant women.
"We are committed to ending this epidemic,” says Dr. Sakoba Keita, national coordinator of the fight against Ebola in Guinea. “Combined with control measures that we are putting in place with our partners, a safe and effective vaccine will allow us to close this trying chapter and start rebuilding our country."
The ring vaccination strategy consists in identifying recently infected patients and vaccinating all their contacts, thereby creating a ‘ring of immunity’ around them to stop the virus from spreading.
“This very same strategy was a key contribution to eradicating smallpox in the 1970’s, and allows us to vaccinate all those at greatest risk," explains WHO coordinator for the Guinea vaccine trial, Dr. Ana Maria Henao Restrepo.
Dr. Bertrand Draguez, medical director for Médecins sans Frontières (MSF) stresses that, “The trial is organized on a voluntary basis, and participation is confidential, free and non-remunerated.”
The Guinean government is fully committed to the success of the vaccine clinical trial. In a March 20 letter addressed to all of the mayors, prefects and local health officials in Guinea, the head of the National Coordination Against Ebola in Guinea, Dr. Sakoba Keita, asked all local public actors for their full cooperation and support.
A total of around 10,000 people are planned to be vaccinated in 190 rings within a six-eight week period. Volunteers will be followed for three months. Results could be available as early as July 2015.
VSV-EBOV Vaccine was developed by the Public Health Agency of Canada. The vaccine was licensed to NewLink Genetics, and on November 24, 2014, NewLink Genetics and Merck announced their collaboration on the vaccine. The concept of ring vaccination applied to the Guinea Ebola vaccine clinical trial is based on vaccinating the “rings” (group of contacts of a newly diagnosed Ebola “index case”) either immediately after confirmation of the Ebola diagnosis of the “index case”, or three weeks later (delayed vaccination). This strategy allows all the known contacts to be vaccinated within a short period of time, and it constitutes an excellent alternative to the use of a placebo. The ring vaccination trial design was developed by an international group of experts from Canada, France, Guinea, Norway, Switzerland, United Kingdom, United States, and WHO. This group included Professor Donald A. Henderson, who led the WHO smallpox eradication effort.