Ebola prime-boost vaccine shows promising results

The first published results from a major Ebola vaccine trial in humans indicate that a new two-part 'prime-boost' vaccine is safe, and could help the immune system to combat the virus.

The study, published in JAMA, was conducted in the UK by the University of Oxford Vaccine Group as part of the EBOVAC1 project consortium, which also includes the London School of Hygiene & Tropical Medicine, Janssen Pharmaceutical Companies of Johnson & Johnson and Inserm, the French National Institute of Health and Medical Research. 

The results show that 100% of healthy adult volunteers taking part in the study achieved an initial antibody response, and this was sustained for at least eight months following prime-boost immunisation. Notably, all participants maintained Ebola-specific antibodies, while vaccine-induced T cell responses (a key marker of immunity) persisted in 77-80% of participants.

Professor Peter Piot, Director of the London School of Hygiene & Tropical Medicine, which is also coordinating trials of the vaccine in Africa, said: "Forty years after the discovery of Ebola, the world still needs an approved vaccine for this disease. A durable prime-boost vaccine could be a vital asset in efforts to proactively protect the general population in countries that are vulnerable to Ebola outbreaks. In light of the persistent challenges that we are seeing with the Ebola virus, durability has become a particularly important goal for vulnerable populations such as health workers and the families of Ebola survivors."

Participants in the study were given an initial 'prime' vaccine dose to prepare the immune system to defend itself against the Ebola virus. This was followed by a second 'boost' dose vaccine of a different type of vaccine to increase the immune response, with the goal of strengthening the duration of immunity.

This is the first set of data from ten clinical studies that are being conducted across the USA, Europe and Africa in support of potential eventual registration for the prime-boost Ebola vaccine. The first study of the prime-boost vaccine in a country affected by the recent Ebola outbreak began in Sierra Leone in October 2015. The clinical studies have been supported by grants awarded by Europe's Innovative Medicines Initiative.

Dr Paul Stoffels, Chief Scientific Officer at Johnson & Johnson said: "The Ebola crisis in West Africa left a huge human cost, we continue to see flare-ups of this disease, and the world needs to be far better prepared for the next major outbreak. This study suggests that Janssen's investigational prime-boost vaccine regimen, if approved by regulators, could be an important tool in global strategies to help prevent another Ebola epidemic."

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