RESULTS from an early Ebola vaccine trial are said to be a "tad disappointing" but show that the drug is safe.

The trial conducted at Oxford University paves the way for the vaccine, jointly developed by GlaxoSmithKline (GSK) and the US National Institutes of Health (NIH), to be further tested on patients in West Africa.

The vaccine uses a single Ebola gene carried in a harmless chimpanzee cold virus to trigger an immune response.

A total of 60 healthy volunteers were inoculated at Oxford University's Jenner Institute between September 17 and November 18 last year.

Findings published in New England Journal of Medicine show the experimental vaccine was well tolerated in three different doses.

Two volunteers experienced a moderate fever which passed within a day.

Although the primary goal of the trial was to assess safety, scientists also measured immune responses to Ebola seen in the participants.

The vaccine was found to generate immunity with levels of antibodies increasing over a period of 28 days.

But independent experts said it did not perform as well as they would have liked.

Molecular virologist Professor Jonathan Ball, from the University of Nottingham, said: "The data have confirmed that the GSK vaccine is well tolerated, with only a small number of people experiencing very minor side effects, which is good news.

"The vaccine was also capable of provoking an immune response, although the overall potency of this response was a tad disappointing.

"The magnitude of the immune responses observed in the vaccine recipients were less than those observed in monkeys that were protected from experimental Ebolavirus infection, but we don't fully understand what degree of immunity humans require in order to protect them from infection.

"That's why clinical trials are important."

Trial leader Professor Adrian Hill, from the Jenner Institute, said larger trials in West Africa would offer more information.

Dr Jeremy Farrar, director of the Wellcome Trust, which co-funded the trial, said: "This study is very encouraging as it provides good initial evidence that the GSK vaccine will be safe to use in people.

"However, we still don't know whether it will provide protection against Ebola infection in a real-world situation.

"That's why trials in West Africa of this, and the other vaccines in development, must begin as soon possible."

Since the start of the outbreak in March last year, Ebola has claimed more than 8,600 lives in Guinea, Liberia and Sierra Leone, Nigeria, Mali and the US.

More than 21,797 cases of the infection have been reported.