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Partnership for Research on Ebola Vaccines in Liberia (PREVAIL)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT02344407
Recruitment Status : Completed
First Posted : January 26, 2015
Results First Posted : August 1, 2017
Last Update Posted : April 8, 2021
Information provided by (Responsible Party):
National Institutes of Health Clinical Center (CC) ( National Institute of Allergy and Infectious Diseases (NIAID) )

Brief Summary:


- Ebola virus disease (EVD) affects many people in Liberia and other countries in West Africa. It is caused by the Ebola virus and makes people sick with fever, headache, vomiting, diarrhea, rash, and bleeding. About half the people with EVD die. There is no approved treatment for it. Researchers are studying two Ebola vaccines. The vaccines do not cause Ebola.


- To study the safety and efficacy of two Ebola vaccines.


- Adults 18 and older who live in Liberia and are at risk for Ebola infection but have never had Ebola.


  • Participants will give information including birthdate, gender, occupation, and location of home. They will give contact information for themselves and 2 alternate contacts. They will give a history of their contact with people with Ebola. Some participants may have a physical. They may have blood taken.
  • Participants will be injected with either an Ebola vaccine or a placebo with a needle in the upper arm. The placebo is a salt solution.
  • Participants will have blood taken.
  • Participants will be watched for 30 minutes.
  • Participants will return to the clinic 1 week and 1 month after they get the shot. They will have blood taken.
  • After that, participants will be contacted monthly to discuss how they are feeling. They may be contacted by phone, may visit the clinic, or may have a home visit.
  • The study ends 8-12 months after participants get the shot. If one of the vaccines works against Ebola and does not have many side effects, participants can get the vaccine if they did not get it in the study.

Condition or disease Intervention/treatment Phase
Ebola Virus Biological: VSVG-ZEBOV Biological: ChAd3-EBO Z Biological: Placebo Phase 2

Detailed Description:

Ebola virus disease (EVD) in West Africa is spreading rapidly, and there is a critical need for a vaccine to prevent EVD. There are two candidate Ebola virus vaccines, the chimpanzee adenovirus 3 (ChAd3-EBO Z)-based vaccine and the Vesicular Stomatitis virus (VSVdeltaG-ZEBOV)-based vaccine. This study will evaluate both of these vaccines in a randomized, double-blind, controlled, 3-arm study in Liberia. Each vaccine will be compared against the same active control. Because there are limited data on the safety of these vaccines, the initial phase (phase 2) of the study will include the collection of more detailed data on safety and will define the immune response elicited by each vaccine in the first 600 volunteers. With the decline in new cases of Ebola virus infection the phase 3 component was no longer deemed to be feasible and, following safety, ethical and FDA approve/concurrence, the study was amended to a more robust, 1,500 person phase 2 design.

With the amendment to only a phasae 3 study the endpoint reverted to the phase 2 endpoint of safety and immunogenicity.

Participants aged 18 year and older will be enrolled at health clinics in Monrovia, Liberia over 4 months. A single dose of the assigned agent will be administered. Participants in phase 2 will undergo blood draw and assessment of adverse events (AEs) and signs and symptoms of Ebola infection at 1 week and 1 month after vaccination, and monthly assessment of AEs and signs and symptoms of Ebola thereafter. Participants in phase 3 will undergo monthly assessment of AEs and signs and symptoms of Ebola infection after vaccination. All participants will be followed for 8 to 12 months.

This clinical trial to evaluate vaccine efficacy will provide an accurate assessment of the benefits and risks associated with each candidate vaccine and inform policy on wider scale vaccination in other countries.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 1500 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary Purpose: Prevention
Official Title: Partnership for Research on Ebola Vaccines in Liberia (PREVAIL)
Study Start Date : January 20, 2015
Actual Primary Completion Date : June 1, 2016
Actual Study Completion Date : November 1, 2020

Arm Intervention/treatment
Experimental: 2
Biological: ChAd3-EBO Z
The ChAd3-EBO Z vaccine is comprised of a ChAd3 vector with a DNA fragment insert that encodes the Ebola virus glycoprotein, which is expressed on the virion surface and is critical for attachment to host cells and catalysis of membrane fusion.

Experimental: 3
Biological: VSVG-ZEBOV
The VSVdeltaG-ZEBOV vaccine is comprised of a single recombinant (vesicular stomatitis virus) VSV isolate (11481 nt) modified to replace the gene encoding the G envelope glycoprotein with the gene encoding the envelope glycoprotein from the Ebola virus Zaire strain (ZEBOV)

Placebo Comparator: 1
Placebo (Saline)
Biological: Placebo

Primary Outcome Measures :
  1. Serious Adverse Events. [ Time Frame: One month ]
    Number of Participants Experiencing Serious Adverse Events in First 30 Days

  2. Immunogenicity Measures (ELISA and Neutralization Antigen-specific Assays for Antibody. [ Time Frame: One month ]
    Antibody Response at 1-Month (EU/mL) for Participants Without Elevated Levels at Entry

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

The inclusion criteria for the study are broad reflecting the target population that would eventually receive an efficacious vaccine.

  • Informed consent
  • Age greater than or equal to 18 years
  • Likely to be in the surrounding area of the vaccination center for at least one year.


  • Fever greater than or equal to 38.0 degrees Celsius
  • History of EVD (self-report)
  • Current pregnancy (a negative urine pregnancy test is required for women of child-bearing potential)
  • Breast-feeding an infant
  • Any condition which would limit the ability of the participant to meet the requirements of the study protocol

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT02344407

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Liberian Ministry of Health and Social Welfare
Monrovia, Liberia
Sponsors and Collaborators
National Institute of Allergy and Infectious Diseases (NIAID)
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Principal Investigator: H. Clifford Lane, M.D. National Institute of Allergy and Infectious Diseases (NIAID)
Publications automatically indexed to this study by Identifier (NCT Number):

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Responsible Party: National Institute of Allergy and Infectious Diseases (NIAID) Identifier: NCT02344407    
Other Study ID Numbers: 999915071
15-I-N071 ( Other Identifier: NIH IRB Protocol ID number )
First Posted: January 26, 2015    Key Record Dates
Results First Posted: August 1, 2017
Last Update Posted: April 8, 2021
Last Verified: March 2021
Keywords provided by National Institutes of Health Clinical Center (CC) ( National Institute of Allergy and Infectious Diseases (NIAID) ):
Zaire Ebola Virus Disease
Additional relevant MeSH terms:
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Hemorrhagic Fever, Ebola
Hemorrhagic Fevers, Viral
RNA Virus Infections
Virus Diseases
Filoviridae Infections
Mononegavirales Infections