The first volunteers of the trial at Centre Hospitalier Universitaire le Dantec in Dakar received an initial vaccination at the start of July, with a booster vaccination one week later. While this is a short timescale for immunisation, if proved successful it would provide an option to respond to an Ebola outbreak with a rapid vaccination programme. This new accelerated vaccination approach is now being tested in parallel in the UK and Senegal.
Dr Egeruan Babatunde Imoukhuede, who is coordinating the Senegal trial, said: ‘The current Ebola outbreak has reinforced that speed of response is crucial. Outbreak diseases spread quickly, so any vaccination approach must be able to keep up.’ There were 30 confirmed cases of Ebola virus disease in West Africa in the week to 5 July 2015 with transmission continuing in Guinea and Sierra Leone, and renewed transmission in Liberia.
The trial uses two vaccines tested first in people at the Jenner Institute at Oxford. The first vaccination, based on a chimpanzee adenovirus (known as ChAd3), is intended to stimulate, or prime, an initial immune response. The second vaccination, using modified vaccinia Ankara (MVA), is designed to boost the level of the body’s immune response further. The ChAd3 vaccine has been developed by GlaxoSmithKline (GSK) and its partners while the MVA vaccine was developed and manufactured through a collaboration between Oxford University, Emergent Biosolutions and GSK and its partners.
Each vaccine is based on genetically modified non-infectious viruses that include a small fragment of the Ebola virus in order to stimulate the body’s immune system to fight the disease. Neither vaccine contains any infectious Ebola virus material, so it cannot cause a person who is vaccinated to become infected with Ebola.
While the Jenner Institute has trialled similar vaccines, this trial uses a refined booster vaccine, explained Professor Adrian Hill, Director of the Jenner Institute: ‘We are using a new MVA, which has two advantages. Firstly, it matches exactly to the ChAd3 insert, which may improve immune responses. Secondly, it was produced on a new cell line that may have many advantages for low cost large scale manufacturing. When you consider that Ebola affects some of the world’s poorer countries and can spread rapidly, getting the scale of manufacturing up while keeping the cost down is key to delivering an effective response.’
In Senegal, Professor Souleymane Mboup is the Principal Investigator (PI) and Head of the Laboratoire de Bactériologie-Virologie (LBV) conducting the study. He said: ‘A dedicated, experienced and seasoned clinical research team led by Dr Pierre Birahim Ndiye has been set in place to work with colleagues at Oxford University for the successful conduct of this Ebola vaccine trial.’
The trials will see around 38 volunteers given the vaccines in the UK, and a further 40 volunteers in Senegal, initially to check that the vaccines have an acceptable safety profile and that they stimulate an immune response. The studies aim to complete enrolment by late August.
The Dakar, Senegal trial is being carried out by the EbolaVac consortium, which includes pharmaceutical company GSK and research partners from the University of Oxford, Centre Hospitalier Universitaire Vaudois in Lausanne and the Bernhard-Nocht Institute, Hamburg. The consortium has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 666085.
The UK trial is being funded by a Wellcome Trust Enhancement Award to Oxford University with co-funding from the UK Department of International Development.