Mass Ebola vaccines for Africa within eight months, says WHO

"All is being put in place to start efficacy tests in the affected countries as early as December," said WHO assistant director general Marie-Paule Kieny, adding that hundreds of thousand of doses could be made available in the "first half" of next year.

Kieny spoke after the UN agency held talks on potential vaccines with medical experts, officials from Ebola-affected nations and other governments, pharmaceutical firms and funding agencies.

"The goal was to discuss and agree how to fast-track the testing and the deployment of promising vaccines in sufficient numbers to use in the field in 2015 to try and impact the Ebola epidemic curve," Kieny said.

Two experimental vaccines are seen as the leading candidates: Canadian-discovered rVSV and ChAd3, made by Britain's GlaxoSmithKline.

Clinical trials of rVSV have already begun in the United States and are set to get underway in Switzerland, Germany, Gabon and Kenya.

ChAd3, meanwhile, is being tested in the United States, Britain and Mali, with further trials due in Switzerland.

WHO staff are being encouraged to play their part in trials, with Kieny among those who have volunteered.

Moves towards field tests are most advanced in Liberia, Kieny said, while plans are also underway for Sierra Leone and Guinea.

The west African countries account for the overwhelming majority of the nearly 10,000 Ebola cases and almost 4,900 fatalities in the worst-ever epidemic of the virus.

"A vaccine is not the magic bullet, but when ready, it may be a good part of the effort to turn the tide of the epidemic," Kieny said.

There are five other potential vaccines in the pipeline in countries including Britain and Russia, with trials expected in the first few months of 2015, Kieny said.

"The pharmaceutical companies developing all these vaccines are committing to ramping up the production capacity to millions of doses to be available in 2015," said Kieny.

Regulators would need to work closely with manufacturers to fast-track the process, she said.

Kieny, who previously said that a vaccine programme could cost "hundreds of millions" of dollars, said "there is a broad understanding that money will not be an issue with this Ebola vaccine."

Mass vaccination in the embattled countries was not on the cards before June, she added.

The initial aim is to help guard health workers against Ebola -- 244 have died so far caring for desperate patients.

"The message we heard from WHO that the people fighting the epidemic will be among the first to test Ebola vaccines and treatments is exactly the one we needed to hear," said Bertrand Draguez, medical director of Doctors Without Borders.