Ebola vaccines: persistence of immunity & response to booster dose of MVA-EBO Z

点击翻译按钮获取中文摘要

The recent Ebola virus outbreak in West Africa resulted in an unprecedented global effort to develop vaccines against this deadly virus, culminating in direct evidence for efficacy for one of the candidate vaccines. This proof that immunisations can protect against Ebola virus infection suggests that they will have a crucial role in the control of future outbreaks of Ebola virus disease.One potential approach to use of these vaccines is pre-emptive immunisation of populations at increased risk of disease, including health care workers (either resident in at-risk areas or as part of international response teams). When used in this way the persistence of vaccine induced immunity is of critical importance to ensure long-term protection against outbreaks, the timing of which are inherently unpredictable.Accordingly in this project we will provide world first data on the persistence of immunity following immunisation with schedules including four of the leading Ebola vaccine candidates. These include MVA-EBO Z, a vaccine developed in Oxford that has a particular role in ‘boosting’ immunity following immunisation with other Ebola vaccines. Furthermore, the immune response to a late booster dose of the MVA-EBO Z vaccine will be evaluated, as will the persistence of this response to 1 year after boosting.To achieve this all 394 participants completing the six phase 1 and 2 Ebola vaccine studies in the UK and Senegal will be invited to participate in these ‘follow-on’ studies, in which blood tests will be taken at 2 to 3 years after initial immunisation. Participants in all but one of these studies will receive a booster dose of MVA-EBO Z, with the remaining group (approximately 35 participants) acting as non-boosted ‘controls’. Blood tests will be taken one month after boosting, with all participants having a further blood test at one year after enrolment. Antibody and cellular immune response will be evaluated at laboratories in Oxford and Senegal.The vaccine trial units at Oxford are particularly well placed to conduct these studies, having administered the ‘first in human’ dose for four of the five vaccines tested in Africa during the recent outbreak. This programme will providing novel data on immune persistence that is essential to the global community’s understanding of how these vaccines can be best deployed to curtail future outbreaks of this devastating illness.