EMA and AMA Recommend Faster Route to Bundibugyo Vaccine Trials

The European Medicines Agency’s Emergency Task Force (EMA-ETF) and the African Medicines Agency (AMA) have issued a joint position paper outlining regulatory and clinical requirements for accelerating the development of vaccines against Bundibugyo virus disease (BVD). The guidance supports faster initiation of clinical trials while maintaining participant safety, with a focus on mRNA and viral-vector vaccines and a potential Phase II/III platform trial using ring vaccination.

Regulatory guidance targets faster vaccine development

The position paper follows a scientific consultation hosted by AMA, EMA and the World Health Organization (WHO) on 24 August 2026. It addresses the need to advance candidate vaccines against Bundibugyo virus (BDBV), a filovirus that causes severe disease and can result in high mortality.

The guidance establishes minimum requirements for entering clinical trials, recommends approaches to streamline preclinical testing and early clinical development, and encourages African national regulatory authorities (NRAs) to accelerate trial assessments. The objective is to move promising candidates into studies involving affected populations without compromising scientific standards or research safeguards.

Platform data could reduce preclinical testing requirements

For vaccines using well-characterised platforms, regulators consider it scientifically justified to defer or waive certain repeat-dose toxicity studies when existing evidence indicates that changing the antigen is unlikely to alter the overall safety profile. This may apply to adenovector-based, vesicular stomatitis virus (VSV)-based and mRNA vaccines, particularly when safety data are available from multiple candidates using the same technology.

Biodistribution studies may also be waived when prior knowledge supports that decision. However, animal immunogenicity data would still be required before clinical trials begin to demonstrate that a candidate can generate an immune response.

These exemptions are not universal. Additional preclinical testing may be necessary if a new antigen presents a potential toxicity risk, the vaccine uses a substantially higher dose or different administration route, or the formulation introduces a previously untested adjuvant.

Animal challenge studies remain important before pivotal trials

Non-human primate studies, particularly in cynomolgus macaques, remain highly relevant for assessing vaccine protection against BDBV. However, limited access to high-containment laboratories has delayed the availability of these data.

The position paper states that such studies are not required before Phase I or Phase II trials but should, in principle, be completed before ring vaccination trials begin. Studies should assess protection following a single vaccination administered 14–28 days before viral challenge.

Ferret models may provide an alternative or complementary source of evidence, subject to case-by-case regulatory assessment. Their ability to reproduce BDBV disease is promising, although the extent to which their immune responses predict human protection remains uncertain.

Early trials prioritise safety and single-dose vaccination

Initial trials should enrol healthy adults and assess safety as the primary endpoint, with immunogenicity as a secondary endpoint. The guidance suggests that early studies may include approximately 20–30 participants per arm, depending on existing platform evidence and the planned development pathway.

Safety monitoring should cover solicited adverse events during the first seven days, unsolicited events during the first month after the final dose, and serious adverse events and events of special interest over six months. For platforms with sufficient prior evidence, safety data from the first two to four weeks may support progression to later-stage trials.

Developers should prioritise single-dose regimens to simplify deployment during outbreaks. Early trials should ideally take place in Africa to facilitate the transition to efficacy studies in affected communities. Trials initiated elsewhere should be followed by, or integrated with, African clinical development as quickly as possible.

 Ring vaccination trials could evaluate multiple candidates

The agencies support randomised ring vaccination studies involving close contacts of confirmed cases, with participants assigned to immediate vaccination or placebo. A shared platform trial could potentially evaluate multiple vaccine candidates, provided that each candidate has an appropriate protocol, control strategy and statistical analysis plan.

Trial protocols should specify interim and final analyses, event thresholds and criteria for progressing from Phase II to Phase III. Comparisons should generally use concurrent controls matched to individual vaccine candidates to reduce the risk of bias.

Children should enter dedicated safety and immunogenicity studies once preliminary four-week adult safety results are available. Pregnant women may be included when existing platform-specific evidence sufficiently supports fetal safety.

Regulatory coordination will shape development timelines

The position paper encourages early engagement with AMA and national regulators to resolve questions about trial design, dose selection, safety monitoring and evidence requirements. Accelerated regulatory and ethics reviews are also recommended in view of the public health emergency.

The guidance provides a pathway for reducing avoidable development delays, but it does not establish the safety or efficacy of any specific BDBV vaccine. Progression towards pivotal trials will still depend on candidate-specific evidence, particularly immunogenicity, safety and protection in relevant animal models.

Reference

AMA and EMA issue joint guidance on Ebola vaccine development, European Medicine Agency, 23 October 2026

Position Paper on Clinical Development of Bundibugyo Vaccines, European Medicine Agency, 23 October 2026