Ebola vaccine has been shown to induce a durable immune response one year after vaccination

The success of the final phase clinical trial, announced in ‘The Journal of the American Medical Association’, shows that the investigational prime-boost vaccine has produced the necessary immune response. The results announced were generated by the EBOVAC1 project supported by the Innovative Medicines Initiative and the Phase 1 study was led by the University of Oxford. The single-centre, randomised, placebo-controlled, observer-blind, Phase 1 trial received approval from the National Research Ethics Service.

The study involved 75 healthy participants aged 18 to 50 years old. 64 attended the follow up 360 days later and all these active vaccine recipients maintained Ebola virus-specify antibody (immunoglobulin G) responses. No serious, vaccine-associated events were observed from day 240 to day 360. Dr Matthew Snape, Chief Investigator of the study, explains this is the longest duration follow-up for any heterologous prime-boost Ebola vaccine regimen yet published.

The vaccine uses a viral vector approach, where a benign virus is modified to safely express key proteins of the target virus, in this case Ebola virus. Prime-boost vaccination is an established approach for the prevention of several infectious diseases.

EBOVAC1 consortium partners include leading global institutions Oxford University, the London School of Hygiene and Tropical Medicine and INSERM, the French National Institute of Health and Medical Research. The project’s aim is to assess the safety and effectiveness, where possible, of a new prime-boost prophylactic vaccine regime against Ebola, which has shown to be 100% effective in preclinical trials.

The project will concentrate on two out of three proposed trials: Phase 1 and Phase 2B. Phase 1 involves 300 people and will establish the initial safety and immunogenicity of the proposed prime-boost regime. In view of the decline in the epidemic and the confirmation of the possibility of a conditional or accelerated licensure approval pathway by the health authorities, Phase Three, the clinical development plan, aims to generate a solid data package. This will consist of substantial immunogenicity and safety data complemented with animal immunogenicity and efficacy data. The trial design will be adapted to focus on safety and immunogenicity and in adults and children.

EBOVAC2 will evaluate the use of the vaccine in special population groups, such as children (ages 1-17 years), the elderly (ages 50-65) and individuals infected with HIV, to confirm safety and immunogenicity. It will also focus on boosting the capacity of African health care centres, staff and infrastructure in preparation for Phase III studies and communicating the results of the project.

A vaccine that provides a durable immune response is important in maintaining a sustained protection against disease, both during outbreaks and outside of an outbreak for at-risk individuals. These include health care and aid workers in areas at risk, individuals from areas experiencing low-grade endemic disease and contacts of Ebola survivors. This is all the more urgent given the evidence of prolonged shedding of the virus in bodily fluids and the consequent potential for transmission.

For more information, please see:
project website