A vaccine against the Ebola virus about to be tested on 30,000 people in West Africa is safe, but has yet to prove its efficacy. It sailed through clinical trials in Britain, the United States, Switzerland and Mali with around 200 healthy volunteers.

Findings published in New England Journal of Medicine show the vaccine generated immunity with levels of antibodies increasing over a period of 28 days. But whether these levels will be enough to counter the virus remains to be seen.

The vaccine uses a type of chimpanzee cold virus as a carrier to deliver benign genetic material from the Zaire strain of the Ebola virus, which is responsible for the recent Ebola outbreak in West Africa.

Since the start of the outbreak in March, Ebola has killed 8,600 people. More than 21,797 cases have been reported. Recently the rate of new infections has declined sharply, suggesting the crisis will soon be over.

University of Nottingham virologist Jonathan Ball described the response of those in the British trial as a “tad disappointing.” The West Africa trials will decide whether the degree of immunity given by the vaccine from British pharmaceuticals company GlaxoSmithKline (GSK) is sufficient to protect people from infection. SAPA