A recent trial of a vaccine to prevent the Ebola virus disease has taken place in the West African state of Guinea, where the latest and most lethal strain originated in late 2013.
Tested on 7,500 people, the vaccine is designed to protect those exposed to the virus as well as others who come in contact with them.
The trial study testing the effectiveness of the drug began on March 7 with the vaccination of Guinean officials. Other frontline personnel have been vaccinated since March 25, beginning with medical workers at the Donka hospital in Conakry, the capital.
Preliminary findings from the Guinea Phase III efficacy vaccine study show that VSV-EBOV, developed by Merck, Sharp & Dohme, is effective against Ebola. This body of international researchers — the Data and Safety Monitoring Board, which conducted the experiment — advised that the trial should move forward. An article published by the British medical journal, The Lancet, says the trial suggested 100 percent effectiveness. (Aug. 3)
Based upon that research report, the vaccine is safe and also provides the first evidence that unvaccinated people may be indirectly protected from Ebola when the VSV-ZEBOV vaccine is provided, using what is categorized as a ring vaccination strategy.
Using the ring methodology, some of those participating in the study are vaccinated for protection soon after an EVD case is diagnosed. Later other participants are vaccinated after a 21-day period. This differs from utilizing a placebo in a randomized control group for comparison, as it guarantees that all contacts are given the vaccine within the course of the trial.
In an article published by Science Daily, Dr. Marie Paule Kieny, co-director of the World Health Organization, was quoted as saying: “Before the trial started, in most clusters there had been a series of Ebola cases over the weeks prior to randomization. However, since the trial started, we have seen no new cases in vaccinated volunteers within 10 days of vaccination, regardless of whether vaccination was immediate or delayed.” (July 31)
WHO Director-General Dr. Margaret Chan said of the trial results: “This is an extremely promising development. 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.” (who.int, July 31)
In the same press release, Dr. Sakoba Keita, the Guinean national coordinator for the EVD response, said of the initial trial: “This is Guinea’s gift to West Africa and the world. 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.”
Although the vaccine is said to have 100 percent effectiveness among those who took part in the trial, additional evidence is still needed to ensure its ability to shield large populations through what is known as “herd immunity.” As a result, the Guinean national regulatory authority and ethics review committee have given the go-ahead for additional research.
EVD outbreak most lethal in history
The latest strain of EVD, one of a number of viral hemorrhagic fevers, has proven by far the most lethal. The disease was first noticed in the Democratic Republic of Congo in 1976.
Subsequent epidemics have come and gone, sparking concern but not nearly as many deaths. Between 1976 and 2013, it was reported that less than 2,500 people had been infected. But since December 2013, there have been over 26,000 cases, resulting in more than 11,000 deaths.
The countries most severely impacted in the West Africa region were Sierra Leone, Liberia and Guinea-Conakry. These states are facing formidable development challenges due to the legacy of colonialism and neocolonialism that have left them without the necessary health care, educational and social services infrastructures as well as trained medical personnel.
Sierra Leone and Liberia underwent extended civil wars during the 1990s and early 2000s in which millions were displaced, among them health care professionals and educators. These countries are yet to recover from these tumultuous events.
Guinea-Conakry, a former French colony, has been the scene of military coups, mutinies and civil unrest since 1984, after the death of its first president, Ahmed Sekou Toure.
A limited number of cases also occurred in the West African states of Nigeria, Senegal and Mali but were rapidly contained.
The outbreak reached its peak during mid-2014, prompting the deployment of thousands of U.S. troops to states already targeted through the U.S. Africa Command (AFRICOM).
Hundreds of Cuban health care professionals volunteered for the relief efforts. They were recognized for their professional and selfless dedication to eliminating the disease.
International cooperation in vaccine trial
The research design used in the trial was developed by a group of experts from Canada, France, Guinea, Norway, Switzerland, Britain, United States and the WHO. The group included Professor Donald A. Henderson of John Hopkins University, who led the WHO smallpox eradication effort using the ring vaccination approach.
Although the initial trial provides promise for containing and eradicating EVD as a major threat to the most severely impacted states, long-term solutions to the crisis must address the need to train medical personnel, build hospitals and clinics as well as construct economies in West African countries that serve the interests of the majority of people.
The Cuban medical personnel, who set high standards in the relief efforts, illustrate the ability of a socialist society to develop scientists, educators and health care workers who operate on a planned basis designed to address the needs of the people. Prioritizing education, research and health care prepares a population for natural and human-made disasters.