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Phase 1 Clinical Trials of NIAID/GSK Investigational Ebola Vaccine

August 28, 2014

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  1. Describe the Ebola vaccine candidate that NIAID will test.
  2. The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), will be testing in early-stage human clinical trials an Ebola vaccine candidate developed by Nancy J. Sullivan, Ph.D., chief of the Biodefense Research Section in NIAID’s Vaccine Research Center (VRC), working in collaboration with a team of VRC researchers and scientists at the Army Medical Research Institute of Infectious Diseases and Okairos, a Swiss-Italian biotechnology company acquired by GlaxoSmithKline in 2013. The candidate, called NIAID/GSK Ebola vaccine, is designed to prevent Ebola virus disease.

    The investigational vaccine is based on a recombinant type of chimpanzee “cold” virus, called chimp adenovirus type 3 (ChAd3). The adenovirus is used as a carrier, or vector, to deliver segments of genetic material derived from two Ebola virus species: Zaire Ebola and Sudan Ebola. The Zaire species of the virus has caused the current Ebola outbreak in West Africa. The vaccine delivers one part of the Ebola genetic material to human cells but the adenovirus vector does not replicate. Rather, the Ebola gene that it carries allows the cells of the vaccine recipient to express a single Ebola protein, and that protein prompts an immune response in the individual.

    NIAID will test two versions of the NIAID/GSK vaccine: a bivalent version containing genetic material derived from the Zaire and Sudan Ebola species and a monovalent version derived from genetic material from only the Zaire Ebola species.

  3. Can a study volunteer injected with the investigational NIAID/GSK Ebola vaccine become infected with Ebola?
  4. No. The Ebola genetic material contained in the investigational vaccine cannot cause someone to become infected with Ebola.

  5. What is the design of the clinical trial, who is the sponsor of the study, and where is it being conducted?
  6. The VRC 207 study is a Phase 1 clinical trial designed to test the safety of the NIAID/GSK investigational Ebola vaccine and its ability to generate an immune system response. Both the bivalent and monovalent versions of the vaccine will be tested in connection with this trial. NIAID is sponsoring the VRC 207 study, which will be led by principal investigator Julie E. Ledgerwood, D.O., chief of the VRC’s clinical trials program. The study will begin testing the bivalent (Zaire and Sudan Ebola species) investigational vaccine during the week of September 1, 2014, at the NIH Clinical Center in Bethesda, Maryland. That portion of the trial will involve 20 healthy adults ages 18 to 50 years. Participants in the study will be divided into two groups (10 participants each). One group will receive an intramuscular injection of the NIAID/GSK experimental vaccine (2x1010 particle units (PU), one milliliter (mL) volume). The second group of 10 participants will also receive a single injection of the experimental vaccine but at a higher dose (2x1011 PU/1 mL).

    Testing of the monovalent version (Zaire Ebola species) of the NIAID/GSK Ebola vaccine candidate is expected to begin in October. That portion of the Phase 1 safety study, which will also involve 20 healthy adults, will be conducted at the NIH Clinical Center and potentially another U.S. site. Dr. Ledgerwood will lead the monovalent vaccine testing as well.

    The VRC 207 trial is being conducted based on expedited review and approval by the U.S. Food and Drug Administration (FDA).

  7. How will the safety of the study participants in the VRC 207 trial be ensured?
  8. The well-being and safety of study participants is always our top priority. To begin, the VRC 207 protocol was independently reviewed by NIAID, the FDA and an institutional review board (IRB). Those reviews were done to ensure that the study would be scientifically, ethically, and clinically appropriate and that it would adhere to accepted standards for protecting human clinical research participants. Volunteers who meet the study’s eligibility criteria must provide oral and written informed consent to participate.

    A number of safety features are built into the study’s design, including daily and weekly reviews of patient data by clinical staff and the study protocol team. Additionally, the trial features a staged enrollment plan that requires interim safety reviews after three participants have been vaccinated and have undergone three days of follow up before enrolling additional study participants into the group. Participants in both groups will be seen and evaluated by clinical staff nine times over a 48-week period.

  9. Is this the first Ebola investigational vaccine to be tested by NIAID?
  10. No. NIAID has developed and tested three earlier investigational Ebola vaccine candidates that began Phase 1 clinical trials in 2003. The NIAID/GSK Ebola vaccine candidate that is being tested in the VRC 207 clinical trial is built upon the knowledge gained from those three earlier clinical trials. Additionally, the two components of the NIAID/GSK vaccine—the chimp adenovirus type 3 vector and the genetic material encoding Ebola glycoprotein—have both been shown to be safe in humans in other Phase 1 trials.

  11. Will tests of the NIAID/GSK investigational Ebola vaccine also be taking place internationally?
  12. Yes. In parallel with the VRC 207 trial, the NIH has partnered with a United Kingdom-based international consortium that includes the Wellcome Trust, the U.K.’s Medical Research Council and the Department for International Development to test the same NIAID/GSK monovalent vaccine candidate. Specifically, the vaccine candidate will be tested among 60 healthy volunteers at the University of Oxford in the United Kingdom and among 40 healthy volunteers in Mali. The University of Maryland School of Medicine Center for Vaccine Development and its Center for Vaccine Development in Mali will conduct the Mali study as a joint enterprise between the University of Maryland School of Medicine and the Ministry of Health of Mali. The vaccine candidate is also expected to be tested among 40 healthy volunteers in Gambia after approval from the relevant authorities.

    The Oxford trial is expected to launch in mid-September pending ethical and regulatory approval.


    Additionally, the U.S. Centers for Disease Control and Prevention has initiated discussions with Ministry of Health officials in Nigeria about the prospects for conducting a Phase 1 safety study of the vaccine among healthy adults in that country.


  13. When do you expect to have data from the Phase 1 safety studies?
  14. The initial safety and immunogenicity data from the Phase 1 NIAID/GSK Ebola vaccine trials are expected by late 2014.

  15. If the safety data is promising, will the NIH make the vaccine available to people working on the frontlines of the Ebola outbreak in West Africa?
  16. There are active discussions underway about when and how to bring experimental interventions into the areas currently affected by Ebola virus disease. NIH believes that it is critical to first obtain Phase 1 safety testing data.

  17. Is NIH testing or supporting research on other Ebola vaccine candidates?
  18. The NIH will also be collaborating with the U.S. Department of Defense in support of efforts by NewLink Genetics Corp., an Ames, Iowa-based biopharmaceutical company, to conduct Phase 1 safety studies of the investigational recombinant vesicular stomatitis virus Ebola vaccine (called VSV-EBOV) developed by and licensed from the Public Health Agency of Canada. Those clinical trials are expected to begin sometime in the fall at the Clinical Trials Center of the Walter Reed Army Institute of Research in Silver Spring, Maryland.

    In addition to the investigational vaccines entering Phase 1 clinical trials, NIAID is supporting the development of other Ebola vaccine candidates. Specifically, NIAID support is assisting Crucell, a Netherlands-based biotechnology company, and Bavarian Nordic, based in Denmark. Crucell is developing a multivalent Ebola/Marburg vaccine using a recombinant adenovirus platform. An initial Phase 1 clinical trial of this candidate vaccine is anticipated to begin by late 2015. Bavarian Nordic is developing a Marburg vaccine using a modified vaccinia Ankara platform, and this vaccine is currently in preclinical development.

    NIAID also is funding Profectus Biosciences, a Baltimore, Maryland-based biotechnology company, to develop a candidate vaccine targeting Ebola and Marburg infections. That product is currently in preclinical testing and is not expected to enter Phase 1 testing in the near-term.

    Investigators from NIAID’s Division of Intramural Research and Thomas Jefferson University in Philadelphia have developed an investigational Ebola vaccine using the established rabies virus vaccine platform​. When tested in mice, the vaccine was strongly immunogenic and provided protection against both Ebola and rabies infection. Three different test versions of the vaccine candidate were found to be safe and to produce potent immune responses against both rabies and Ebola viruses when tested in nonhuman primates. Additionally, the three versions of the vaccine candidate conferred 50 to 100 percent protection from Ebola infection in nonhuman primates. NIAID-supported researchers are currently pursuing the development of multivalent vaccine candidates against Ebola, Marburg and rabies viruses for use in humans.

Media inquiries can be directed to the NIAID Office of Communications at 301-402-1663,


NIAID conducts and supports research—at NIH, throughout the United States, and worldwide—to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses. News releases, fact sheets and other NIAID-related materials are available on the NIAID website.

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit

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Last Updated August 28, 2014

Last Reviewed August 28, 2014