In response to the “devastating outbreak” of Ebola in West Africa, U.S. National Institutes of Health (NIH) Director Francis Collins has announced “extraordinary measures to accelerate the pace of vaccine clinical trials.”
At a teleconference this morning, Collins and Anthony Fauci, head of NIH’s National Institute of Allergy and Infectious Diseases (NIAID), described several human studies of different Ebola vaccines that will begin over the next few months. None of these clinical trials will determine whether the vaccines work. Instead, the goal will be to assess whether they are safe and stimulate immune responses. Several Ebola vaccines have been tested in humans but none have moved forward to large-scale efficacy studies.
The first trial will begin next week at the NIH Clinical Center in Bethesda, Maryland. The vaccine, developed by NIAID’s Vaccine Research Center and GlaxoSmithKline, contains genes for the surface protein from two strains of Ebola virus—including the Zaire one now in West Africa—stitched into an adenovirus that infects chimpanzees. As Fauci explained, the chimp adenovirus does not copy itself but acts as a vector and delivers the Ebola genes to human cells, which then should make proteins that trigger an immune response. The vaccine has shown “very good protection” in monkey tests, Fauci noted.
This first study will involve 20 volunteers who will receive the vaccine at two different doses. Fauci says the researchers hope to have initial data available by the end of the year, although the study will monitor the participants for 48 weeks. In October, NIAID will begin tests with a simpler, monovalent version of the same vaccine that only contains a surface protein gene from the Zaire strain of Ebola.
Fauci said tests of the monovalent vaccine would soon begin in England, Mali, and Gambia in collaboration with a consortium in the United Kingdom that includes the Wellcome Trust and that country’s Medical Research Council. These tests similarly will only test safety and immune responses. The three studies together will involve 140 people.
Mali and Gambia do not currently have any Ebola cases, and Fauci said they were chosen because they had the infrastructure to conduct the studies. The three West African countries hardest hit by the current outbreak—Liberia, Guinea, and Sierra Leone—“would not allow the careful kind of phase I study you want to do,” Fauci said. Nigeria, which also is affected by the current outbreak, is another possible site for phase I vaccine studies, he added.
A phase I study with a different vaccine, one that uses vesicular stomatitis virus as the vector to deliver Ebola genes, also will begin this fall, Fauci said. The human tests of that vaccine, developed by Canada’s public health agency, will take place at the Walter Reed Army Institute of Research in Silver Spring, Maryland.
Fauci stressed that these small early studies are designed to make sure these potential vaccines do not cause harm. “I have been fooled enough in my many years of experience in infectious disease and vaccinology that you really can’t predict what you might see,” Fauci said. “The worst thing … is to let something widely out before you’ve even tested a modicum of safety. That would violate scientific principles and, in many respects, even ethical principles.”
*The Ebola Files: Given the current Ebola outbreak, unprecedented in terms of number of people killed and rapid geographic spread, Science and Science Translational Medicine have made a collection of research and news articles on the viral disease freely available to researchers and the general public.