PREVAIL I Cluster Vaccination Study With rVSVΔG-ZEBOV-GP as Part of a Public Health Response in Liberia.

OBJECTIVE: In November 2015, a 15-year-old boy received a diagnosis of Ebola virus disease (EVD) at the John F. Kennedy Medical Center in Monrovia, Liberia. Two additional family members received a diagnosis of EVD. The protocol for a phase 2 placebo-controlled trial of 2 Ebola vaccines was amended and approved; in 4 days, a single-arm cluster vaccination trial using the Merck rVSVΔG-ZEBOV-GP vaccine was initiated. Here, we evaluate the safety and immunogenicity of the vaccine and discuss challenges for its implementation in a small Ebola outbreak. METHOD: We conducted a ring vaccination study among contacts and contacts of close contacts of EVD cases a in Monrovia. Participants were evaluated 1 and 6 months after vaccination. RESULTS: Among 650 close contacts and contacts of close contacts of EVD cases, 210 (32%) consented and were vaccinated with rVSVΔG-ZEBOV-GP. Of those vaccinated, 189 (90%) attended the month 1 follow-up visit; 166 (79%) attended the month 6 visit. No serious adverse events were reported. Among 88 participants without an elevated antibody level at baseline, 77.3% (95% confidence interval, 68.5-86.1) had an antibody response at 1 month. CONCLUSIONS: The Merck rVSVΔG-ZEBOV-GP vaccine appeared to be safe and immunogenic among the vaccinated individuals. However, fewer than one third of eligible individuals consented to vaccination. These data may help guide implementation decisions for of cluster vaccination programs in an Ebola cluster outbreak response situation.

Conventional Wisdom versus Actual Outcomes: Challenges in the Conduct of an Ebola Vaccine Trial in Liberia during the International Public Health Emergency.

Clinical trials are challenging endeavors. Planning and implementing an investigational vaccine trial in Liberia, in the midst of an Ebola virus disease (EVD) epidemic that World Health Organization classified a public health emergency of international concern, presented extraordinary challenges. Normally, years of preparation and a litany of tasks lay the groundwork for a successful, randomized, blinded, placebo-controlled trial focused on safety and efficacy. Difficult research settings, unpredictable events, and other unique circumstances can add complexity. The setting in Liberia was especially problematic due to an infrastructure still badly damaged following a lengthy civil war and a very fragile health-care system that was further devastated by the EVD outbreak. The Partnership for Research on Vaccines in Liberia I EVD vaccine trial was planned and implemented in less than 3 months by a Liberian and U.S. research partnership, and its Phase II substudy was fully enrolled 3 months later. Contrasting conventional wisdom with trial outcomes offers an opportunity to compare early assumptions, barriers encountered, and adaptive strategies used, with end results. Understanding what was learned can inform future trial responses when disease outbreaks, especially in resource-poor locations with minimal infrastructure, pose a significant threat to public health.

Implementation of an Ebola virus disease vaccine clinical trial during the Ebola epidemic in Liberia: Design, procedures, and challenges.

The index case of the Ebola virus disease epidemic in West Africa is believed to have originated in Guinea. By June 2014, Guinea, Liberia, and Sierra Leone were in the midst of a full-blown and complex global health emergency. The devastating effects of this Ebola epidemic in West Africa put the global health response in acute focus for urgent international interventions. Accordingly, in October 2014, a World Health Organization high-level meeting endorsed the concept of a phase 2/3 clinical trial in Liberia to study Ebola vaccines. As a follow-up to the global response, in November 2014, the Government of Liberia and the US Government signed an agreement to form a research partnership to investigate Ebola and to assess intervention strategies for treating, controlling, and preventing the disease in Liberia. This agreement led to the establishment of the Joint Liberia-US Partnership for Research on Ebola Virus in Liberia as the beginning of a long-term collaborative partnership in clinical research between the two countries. In this article, we discuss the methodology and related challenges associated with the implementation of the Ebola vaccines clinical trial, based on a double-blinded randomized controlled trial, in Liberia.