The Center for Vaccine Development (CVD), in conjunction with its sister institution, the Center for Vaccine Development of Mali (CVD-Mali) and the Ministry of Health of Mali, have begun a clinical trial in health care workers (and other front-line workers) to evaluate a promising experimental Ebola vaccine.

The trial began on Wednesday, Oct. 8 with the vaccination of the first subject, followed by two additional participants Oct. 9, all three being Malian health care workers. In the coming weeks, 37 more health care workers will receive the vaccine.

"This research will give us crucial information about whether the vaccine is safe, well-tolerated and capable of stimulating adequate immune responses in the highest priority target population, health care workers in West Africa," said professor Myron M. Levine, M.D., director of the Center for Vaccine Development (CVD) at the University of Maryland School of Medicine (UM SOM). "If it works, in the foreseeable future it could help alter the dynamic of this epidemic by interrupting transmission to health care and other exposed front-line workers."

The vaccine consists of an adenovirus (cold virus) that does not cause illness in humans and has been modified so that it cannot even multiply in humans but produces a single attachment protein of Ebola virus. Immune responses directed against this single Ebola protein have been shown to be highly protective in animal model challenge studies (carried out under the highest level of physical containment). Researchers hope this response will be robust enough to protect humans, as well, from the disease.

The vaccine was developed by investigators at the Vaccine Research Center (VRC) of the National Institute of Allergy and Infectious Diseases (NIAID) in Bethesda, Md. The clinical trial in Mali brings to fruition two months of work by a consortium dedicated to move the candidate Ebola vaccine (which prior to September had been tested only in animals but not in humans) into clinical studies in West Africa.

The consortium, assembled in mid-August at the behest of the World Health Organization (WHO), included, besides WHO, the VRC (which developed the vaccine), the Jenner Institute at the University of Oxford (which carried out clinical trials in U.K. adults paving the way for the African trial), the CVD-UM SOM and CVD-Mali (carrying out the first clinical trial of the vaccine in West Africa), GlaxoSmithKline Biologicals (manufacturer of the vaccine) and the Wellcome Trust, U.K. (funder of the clinical trials in U.K. and Mali), with additional funding provided by the Medical Research Council (MRC), U.K. and the U.K. Department for International Development (DFID).

In addition, the MRC Unit-The Gambia is expected soon to initiate a second, parallel clinical trial in The Gambia, West Africa. Ordinarily it would take between six to 11 months to obtain all necessary ethical, regulatory agency, technical and administrative approvals needed to transition a vaccine from research in animal models to a clinical trial in a developing country where subjects are at risk of the natural disease. In this instance, with all consortium members working in unison, it took two months.

"This is just the critical first step in a series of additional clinical trials that will have to be carried out to fully evaluate the promising vaccine," said professor Samba Sow, director general of CVD-Mali. "However, if it is eventually shown to work and if this information can be generated fast enough, it could become a public health tool to bring the current, and future, Ebola virus disease epidemics under control."

Preclinical research in primates by the VRC and Okairos, a biotechnology company acquired last year by GSK, indicate that the vaccine provides protection in non-human primates exposed to Ebola without significant side effects. The recent increase in funding for Ebola vaccine research also is enabling GSK to begin manufacturing at least 10,000 additional doses of the vaccine, even as the first clinical trials are occurring.