"An experimental Ebola vaccine was highly protective against the deadly virus in a major trial in Guinea according to results published today in The Lancet. The vaccine is the first to prevent infection from one of the most lethal known pathogens and the findings add weight to early trial results published last year.  The vaccine called rVSVZEBOV  was studied in a trial involving  people in Guinea during . Among the  people who received the vaccine no Ebola cases were recorded  days or more after vaccination . In comparison there were  cases  days or more after vaccination among those who did not receive the vaccine.  The trial was led by the World Health Organization together with Guineas Ministry of Health and other international partners. While these compelling results come too late for those who lost their lives during West Africas Ebola epidemic they show that when the next Ebola outbreak hits we will not be defenceless said Dr MariePaule Kieny WHOs Assistant DirectorGeneral for Health Systems and Innovation and the studys lead author .  The vaccines manufacturer Merck Sharpe  Dohme this year received Breakthrough Therapy Designation from the United States Food and Drug Administration and PRIME status from the European Medicines Agency enabling faster regulatory review of the vaccine once it is submitted.  Since Ebola virus was first identified in  sporadic outbreaks have been reported in Africa. But the  West African Ebola outbreak which resulted in more than  deaths highlighted the need for a vaccine.  The trial took place in the coastal region of BasseGuine the area of Guinea still experiencing new Ebola cases when the trial started in . The trial used an innovative design a socalled ring vaccination approach  the same method used to eradicate small pox.  When a new Ebola case was diagnosed the research team traced all people who may have been in contact with that case within the previous  weeks such as people who lived in the same household were visited by the patient or were in close contact with the patient their clothes or linen as well as certain contacts of contacts. A total of  clusters or rings were identified each made up of an average of  people.  Initially rings were randomised to receive the vaccine either immediately or after a week delay and only adults over  years were offered the vaccine. After interim results were published showing the vaccines efficacy all rings were offered the vaccine immediately and the trial was also opened to children older than  years. In addition to showing high efficacy among those vaccinated the trial also shows that unvaccinated people in the rings were indirectly protected from Ebola virus through the ring vaccination approach socalled herd immunity. However the authors note that the trial was not designed to measure this effect so more research will be needed.  Ebola left a devastating legacy in our country. We are proud that we have been able to contribute to developing a vaccine that will prevent other nations from enduring what we endured said Dr Keta Sakoba Coordinator of the Ebola Response and Director of the National Agency for Health Security in Guinea . To assess safety people who received the vaccine were observed for  minutes after vaccination and at repeated home visits up to  weeks later. Approximately half reported mild symptoms soon after vaccination including headache fatigue and muscle pain but recovered within days without longterm effects. Two serious adverse events were judged to be related to vaccination a febrile reaction and one anaphylaxis and one was judged to be possibly related influenzalike illness. All three recovered without any long term effects. It was not possible to collect biological samples from people who received the vaccine in order to analyse their immune response. Other studies are looking at the immune response to the vaccine including one conducted in parallel to the ring trial among frontline Ebola workers in Guinea.  This both historical and innovative trial was made possible thanks to exemplary international collaboration and coordination the contribution of many experts worldwide and strong local involvement said Dr JohnArne Rttingen Specialist Director at the Norwegian Institute of Public Health and the chairman of the study steering group .  In January GAVI the Vaccine Alliance provided US million to Merck towards the future procurement of the vaccine once it is approved prequalified and recommended by WHO. As part of this agreement Merck committed to ensure that  doses of the vaccine are available for emergency use in the interim and to submit the vaccine for licensure by the end of . Merck has also submitted the vaccine to WHOs Emergency Use and Assessment Listing procedure a mechanism through which experimental vaccines medicines and diagnostics can be made available for use prior to formal licensure. Additional studies are ongoing to provide more data on the safety of the vaccine in children and other vulnerable populations such as people with HIV. In case of Ebola flareups prior to approval access to the vaccine is being made available through a procedure called compassionate use that enables use of the vaccine after informed consent. Merck and WHOs partners are working to compile data to support license applications.  The rapid development of rVSVEBOV contributed to the development of WHOs RD Blueprint a global strategy to fasttrack the development of effective tests vaccines and medicines during epidemics.  Also published in The Lancet embargo as above is a phase  trial of a different Ebola vaccine candidate the recombinant adenovirus type Ebola vaccine. The trial was led by the Beijing Institute of Biotechnology and was conducted in Sierra Leone in . It involved  healthy participants followed for  months   were given a high dose vaccine  a lowdose and  a placebo. The study found that the vaccine was safe and induced an immune response that peaked at  days but decreased during the six months post injection. One serious adverse event was reported in an individual with a history of asthma. Further research on this vaccine is needed in order to assess its efficacy.   NOTES TO EDITORS  The rVSVZEBOV trial is funded by WHO with support from the Wellcome Trust the United Kingdom Department for International Development the Norwegian Ministry of Foreign Affairs to the Norwegian Institute of Public Health through the Research Council of Norway the Canadian Government through the Public Health Agency of Canada Canadian Institutes of Health Research International Development Research Centre and Department of Foreign Affairs Trade and Development and Mdecins Sans Frontires. The trial team includes experts from The University of Bern the University of Florida the London School of Hygiene and Tropical Medicine Public Health England the European Mobile Laboratories among others. The trial was designed by a group of experts including the late Professor Donald A. Henderson of John Hopkins University who led the WHO smallpox eradication effort by using the ring vaccination strategy.  http   VSVEBOV was developed by the Public Health Agency of Canada. The vaccine was licensed to NewLink Genetics who in turn licensed it to Merck  Co. The vaccine works by replacing a gene from a harmless virus known as vesicular stomatitis virus VSV with a gene encoding an Ebola virus surface protein. The vaccine does not contain any live Ebola virus. Earlier trials have shown the vaccine to be protective in animals and be safe and produce an immune response in humans.   Analysis only included cases occurring  days after receiving the vaccine to account for the incubation period of the Ebola virus.   Quotes direct from authors and cannot be found in the text of the Article."