The French National Institute of Health and Medical Research (Inserm), the US National Institutes of Health (NIH) and the London School of Hygiene & Tropical Medicine (LSHTM), in collaboration with health authorities in Guinea and Liberia, are launching a large clinical trial of candidate Ebola vaccines under the aegis of the PREVAC international consortium (Partnership for Research on Ebola VACcination).

This trial seeks to identify vaccination regimens that hold the most promise to protect people from Ebola virus disease in order to prevent or quickly control a future outbreak. More than 5,000 adults and children living in countries at the epicenter of the 2014–16 West Africa Ebola epidemic will be enrolled. An additional site in Sierra Leone is also being planned. The PREVAC trial results from a research partnership that involves Inserm, NIH, LSHTM, and the West African Clinical Research Consortium. The pharmaceutical companies Janssen Vaccines & Prevention B.V., part of the Janssen Pharmaceutical Companies of Johnson & Johnson, Bavarian Nordic and Merck Sharp & Dohme, Corp (MSD outside USA and Canada), are supplying the experimental vaccines being tested in the PREVAC trial.

The trial will compare three experimental Ebola vaccination strategies with placebo regimens. It will be conducted in two stages, the first stage to take place in Guinea and Liberia. In Guinea, the trial is being conducted under the sponsorship of Inserm with the support of NIH and in collaboration with the Guinean authorities, and involves a partnership with the non–governmental organization ALIMA (The Alliance for International Medical Action). The NIH is sponsoring the trial based in Liberia, under its collaboration with the Liberia Ministry of Health in the Partnership for Research on Ebola Virus in Liberia (PREVAIL). Pending confirmation of funding, LSHTM will sponsor the planned site in Sierra Leone working with the University of Sierra Leone’s College of Medicine and Allied Health Sciences, which would conduct the study.

In its first stage, the trial will evaluate one of the three strategies, a prime–boost vaccination combining two different vaccines (one made by Janssen and the other by Bavarian Nordic) compared with a similar placebo regimen. Enrolment into this stage in Guinea and Liberia began on 27th March and 3rd April 2017, respectively. In a second stage, which is expected to start in the second half of 2017, the trial will evaluate all three vaccination strategies, including two additional strategies involving the Merck Sharp & Dohme, Corp vaccine.