Large-scale human testing of two potential Ebola vaccines got underway in Liberia's capital city of Monrovia on Monday, part of a global effort to prevent a repeat of the epidemic that has claimed nearly 9,000 lives in West Africa.

The studies in Liberia are taking place after smaller-scale tests determined that the vaccines were safe for human use. By comparing them now with a dummy shot, scientists hope to learn whether they can prevent people from contracting the deadly virus that has killed about 60 percent of those hospitalized for it.

Yet despite the trials' promise, authorities still must combat fear and suspicion that people could become infected by taking part. Each vaccine uses a different virus to carry non-infectious Ebola genetic material into the body and spark an immune response.

On Sunday in one densely populated neighborhood of Monrovia, musicians sang songs explaining the purpose and intent of the trial in a bid to dispel fears.

B. Emmanuel Lansana, 43, a physician's assistant, was the first to receive doses on Monday. Two shots were administered at different points on his right arm. His wife had expressed apprehension about the vaccine trial, but Lansana said he still wanted to participate.

"From the counseling, all of the reservations I have were explained, my doubts were cleared," he said in a room where he was being observed for 30 minutes afterward.

Up to 600 volunteers are taking part in the first phase, and trial organizers have said eventually as many as 27,000 people could join.

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 and joint pain, and loss of appetite.

"We are targeting about 12 persons for today and hopefully the number will increase as we go along," Wissedi Sio Njoh, director of operation with the vaccination campaign, told The Associated Press.

The World Health Organization says the Ebola epidemic has infected more than 22,000 people and claimed more than 8,800 lives over the past year. Without a vaccine, officials have fought the outbreak with old-fashioned public health measures including isolating the sick, tracking and quarantining those who had contact with them, and setting up teams to safely bury bodies.

Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, has said both experimental vaccines showed promise in first-stage human safety tests. One was developed by the National Institutes of Health and is being manufactured by GlaxoSmithKline. The other was developed by Canadian health officials and is licensed to two U.S. companies, NewLink Genetics and Merck.

The vaccine trials come as the three most affected countries — Guinea, Sierra Leone and Liberia — appear to be making strides against the Ebola epidemic first identified last March. The U.N. health agency said last week that the countries had reported fewer than 100 cases in the past week, for the first time since June.

However, Liberia's education ministry said Sunday it would postpone by two weeks the reopening of the country's schools, which were closed six months ago to limit the spread of the Ebola virus.

Schools in Guinea and Sierra Leone were also closed last year over the outbreak.

Last week, the Red Cross said in a Geneva news briefing that many West Africans remain suspicious of aid workers, especially in Guinea — a situation that is causing the virus to flare up in new areas.

"I think that we should consider ourselves lucky and fortunate if we are able to stop [Ebola] in 2015," said Birte Hald, who leads the Ebola coordination and support unit of the International Federation of Red Cross and Red Crescent Societies.

Wire services