Partnership for Research on Ebola VACcination

Partnership for Research on Ebola VACcination (PREVAC) is an international consortium established to conduct large-scale clinical trials for Ebola virus disease vaccines. Launched in response to the devastating 2013–2016 Ebola virus epidemic in West Africa, the partnership aimed to rapidly generate robust data on vaccine safety and immunogenicity. Its work has been pivotal in advancing the World Health Organization's R&D Blueprint for Action to Prevent Epidemics and informing global preparedness strategies.

Background and formation

The initiative was conceived amid the unprecedented scale of the West African Ebola virus epidemic, which exposed critical gaps in the availability of proven medical countermeasures. Prior to this outbreak, Ebola vaccine development had been slow, with candidates like rVSV-ZEBOV primarily in early-phase trials. The international emergency prompted a coordinated response from global health agencies, leading to the creation of PREVAC in 2014. Key drivers included the National Institutes of Health, the French Institute of Health and Medical Research (Inserm), and the London School of Hygiene & Tropical Medicine, who recognized the urgent need for definitive efficacy trials. The partnership was formally established to operate under a collaborative protocol across multiple affected countries, including Guinea, Liberia, Sierra Leone, and later Mali.

Objectives and design

The primary objective of PREVAC was to evaluate the safety and immunogenicity of promising Ebola vaccine regimens in a large population, including children. A core scientific goal was to determine the durability of the immune response and compare different vaccination strategies, such as prime-boost schedules. The initiative employed a randomized, double-blind, placebo-controlled trial design, considered the gold standard in clinical research. Studies were specifically designed to assess regimens involving vaccines like rVSV-ZEBOV and the Ad26.ZEBOV/MVA-BN-Filo combination, with follow-up over multiple years. This design was intended to provide data that could support regulatory approval by bodies like the European Medicines Agency and inform vaccination policies for future outbreaks.

Participating organizations

PREVAC is a multi-stakeholder consortium bringing together leading public health and research institutions. Core leadership and funding were provided by the National Institute of Allergy and Infectious Diseases (NIAID) and Inserm. Operational research and trial coordination were managed by experts from the London School of Hygiene & Tropical Medicine and the University of Oxford. In West Africa, critical implementation partners included the Centre pour le Développement des Vaccins in Mali and national ministries of health in Liberia and Guinea. Additional support came from the Biomedical Advanced Research and Development Authority (BARDA) and the Wellcome Trust. The trials were conducted in close collaboration with the World Health Organization and local ethical review boards.

Key trials and findings

The consortium's flagship study, the PREVAC trial, began in 2017 and enrolled thousands of participants across sites in Liberia, Sierra Leone, Guinea, and Mali. It directly compared three regimens: a single dose of rVSV-ZEBOV, the Ad26.ZEBOV/MVA-BN-Filo prime-boost, and placebo. Interim results published in the New England Journal of Medicine demonstrated that both vaccine regimens induced strong antibody responses that persisted for at least one year. The Ad26.ZEBOV/MVA-BN-Filo regimen showed particularly durable immunity, a key finding for long-term protection. The trial also provided crucial safety data in diverse populations, including children as young as one year old, filling a significant evidence gap. These findings contributed directly to the European Medicines Agency approval of both vaccine regimens.

Impact and legacy

PREVAC's work has had a profound impact on the field of epidemic preparedness and vaccinology. The robust data generated accelerated the licensure of multiple Ebola vaccines, which were subsequently deployed during the Kivu Ebola epidemic in the Democratic Republic of the Congo. The partnership established a lasting clinical trial infrastructure and trained a cohort of local researchers in West Africa, strengthening regional capacity. Its collaborative model is now seen as a blueprint for rapid-response research during health emergencies, influencing frameworks like the Coalition for Epidemic Preparedness Innovations (CEPI). The legacy of PREVAC endures in the World Health Organization's Immunization, Vaccines and Biologicals department guidelines and in the strategic vaccine stockpiles maintained for future Ebola virus disease outbreaks.

Category:Medical research organizations Category:Ebola Category:Vaccination