The epidemic has killed more than 8,900 people in West Africa since it began more than a year ago, overwhelming weak healthcare systems in Guinea, Liberia and Sierra Leone. Its spread now appears to be slowing, especially in Liberia which has reported just 15 new cases in the past 21 days.
The trial to test two vaccines from GlaxoSmithKline and New Link/Merck began at the government-run
Redemption Hospital in Monrovia, a cluster of cement blocks in the teeming New Kru Town neighbourhood that was one of the first parts of the capital to be struck by the disease.
"I do not want for Ebola to affect my family and so I have
come to volunteer," said Zolu McGill, among the first batch of four volunteers seen at the hospital by a Reuters reporter.
Several doctors and the country's information minister Lewis Brown plan to be vaccinated on Tuesday.
But Liberia's Deputy Health Minister Tolbert Nyenswah said he did not expect the vaccines to make a difference in the current outbreak. "What will end this outbreak are the measures that we are taking now - the Ebola treatment units, the contact tracing, the engagement in the community and social mobilisation. That is what is getting us to zero."
Scientists say the study, a final stage trial which hopes to involve 27,000 volunteers at the heart of the epidemic after earlier safety trials in the UK, United States and other African countries, could be a turning point in the fight against the deadly virus, which has no known cure.
But given relatively few new cases in the dwindling outbreak, researchers are concerned the trial in Liberia, plus another planned in Sierra Leone, may not have the statistical power needed to show whether the shots work.
Volunteers will receive a small compensation package. Each of the vaccines contains a small harmless portion of the Ebola virus and may cause side effects in some people such as pain, redness, fever, headaches, mouth sores, tiredness, muscle, joint pain and loss of appetite.
The Partnership for Research on Ebola Vaccines (Prevail) says healthy volunteers above 18 years old who have no previous history of the virus will be selected.
Hopes of defeating Ebola
Vice President Joseph Boakai said in a speech on Sunday attended by dignitaries that he hoped the successful development of drugs would prevent any other country from suffering the devastation experienced by Liberia.
"It's our conviction that from this worthy exercise humankind will prevail over the deadly killer of man," he said.
The slowdown in the epidemic is already hampering drug development. Chimerix Inc said on Friday it was stopping participation in clinical studies in Liberia of a drug, brincidofovir, to treat people who already have Ebola, citing the slump in new cases.
With that in mind, and looking ahead to future potential outbreaks, scientists are thinking about how to develop and test second-generation Ebola vaccines, which could be used to prevent more strains of the disease than the current fast-tracked shots.
Some scientists and aid workers are calling for trials to begin promptly in neighbouring Sierra Leone where transmission hotspots exist around the capital Freetown.
The U.S. ambassador to Liberia, Deborah Malac, said that cooperation on the vaccines represented an opportunity for greater cooperation between the two countries on clinical research and developing the Liberian health system.
"It's fantastic that large-scale trials of the first candidate Ebola vaccine are getting underway in Liberia, a country that has suffered enormously at the hands of this disease," said Jeremy Farrar, Director of the Wellcome Trust, which is funding a trial of the GSK vaccine in Britain and Mali.
