Washington, D.C., September 8, 2014 (AMG) – An experimental Ebola vaccine is being tested on healthy volunteers in the US, following promising trial results showing ‘long term’ immunity in monkeys.
The treatment being developed has so far demonstrated immunity in four macaque monkeys who were exposed to a lethal dose of Ebola infection, five weeks after being given the vaccine. Results suggest that immunity could last up to ten months, but this may require one or two booster injections.
Human trials to determine the vaccine’s safety began this week in the US and have been fast tracked to go ahead in the UK, Mali and the Gambia. The first participant was a 39 year old American woman. Only one vaccine will be administered to participants with further trials necessary to monitor the effects of booster injections for longer term immunity. Safety data for this trial should be ready by November this year when, if acceptable, up to 10,000 doses may be available for use in West Africa with immediate effect.
Public health emergency: The speed that ethical approval has been given indicates the severity of the public health emergency. Last Thursday, WHO met to discuss how to evaluate and when to use the experimental treatments currently available. They warn that promising developments in Ebola treatment should not detract from other public health measures, including hand washing and the isolation of infected people.
This vaccine is being developed by the National Institute of Health and a Swiss company bought by GlaxoSmithKline last year. It uses a genetically modified chimp virus containing Zaire ebolavirus, which caused the current outbreak in West Africa, and a second type called Sudan ebolavirus. The viral vaccine does not replicate inside the body, meaning it is not infectious and does not cause symptoms, however it does express a protein that – it is hoped – the body will develop immunity to.
Other treatment trials: A separate vaccine trial being carried out by Johnson & Johnson is due to begin in early 2015, much earlier than previously expected, and a vaccine developed by Canadian government scientists will begin human trials this autumn. WHO has said that the experimental drug ZMapp will also be tested in West Africa treatment centres as a protocol is developed, and that serum from the blood of those who have recovered from Ebola infection should be used in treatment.
This follows calls by the head of the World Bank to step up the response as over 2,000 people have now died from the infection with no signs that the epidemic is slowing. Dr. Marie-Paule Kieny, an assistant director general at WHO, says, “we have to change the sense there is no hope in this situation to a realistic hope. One of the things driving fear and panic in the communities and the world is the belief there is no treatment.”