Vaccine success holds hope for end to deadly scourge of Ebola

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Breakthrough Ebola Vaccine Discovered

The world is on the verge of being able to protect humans against Ebola, the World Health Organization said on Friday, as a trial in Guinea found a vaccine to have been 100 percent effective.

Initial results from the trial, which tested Merck (MRK.N) and NewLink Genetics' (NLNK.O) VSV-ZEBOV vaccine on some 4,000 people who had been in close contact with a confirmed Ebola case, showed complete protection after 10 days.

The results were described as "remarkable" and "game changing" by global health specialists.

See photos of the vaccine trial:

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Ebola vaccine in Guinea
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Vaccine success holds hope for end to deadly scourge of Ebola
A health worker prepares a vaccination on March 10, 2015 at a health center in Conakry during the first clinical trials of the VSV-EBOV vaccine against the Ebola virus. The World Health Organization (WHO) said on March 5 that clinical trials launched on March 7 in Guinea marked the last step before the vaccine is available on the market. AFP PHOTO / CELLOU BINANI (Photo credit should read CELLOU BINANI/AFP/Getty Images)
A woman gets vaccinated on March 10, 2015 at a health center in Conakry during the first clinical trials of the VSV-EBOV vaccine against the Ebola virus. The World Health Organization (WHO) said on March 5 that clinical trials launched on March 7 in Guinea marked the last step before the vaccine is available on the market. AFP PHOTO / CELLOU BINANI (Photo credit should read CELLOU BINANI/AFP/Getty Images)
A woman gets vaccinated on March 10, 2015 at a health center in Conakry during the first clinical trials of the VSV-EBOV vaccine against the Ebola virus. The World Health Organization (WHO) said on March 5 that clinical trials launched on March 7 in Guinea marked the last step before the vaccine is available on the market. AFP PHOTO / CELLOU BINANI (Photo credit should read CELLOU BINANI/AFP/Getty Images)
FILE - In this March 7, 2015 file photo, a health worker, right, cleans a man's arm before injecting him with a Ebola vaccine in Conakry, Guinea. An experimental vaccine tested on thousands of people in Guinea exposed to Ebola seems to work and might help shut down the ongoing epidemic in West Africa, according to interim results from a study published Friday, July 31, 2015. There is currently no licensed treatment or vaccine for Ebola, which has so far killed more than 11,000 people in West Africa since the worldâs biggest outbreak began last year. (AP Photo/ Youssouf Bah, File)
FILE In this Monday, Jan. 19, 2015 file photo, a health care worker, right, takes the temperatures of school children for signs of the Ebola virus before they enter their school in the city of Conakry, Guinea. The World Health Organization says it will soon start large-scale testing of an experimental Ebola vaccine in Guinea to see how effective it might be in preventing future outbreaks of the dreaded virus. In a statement issued on Thursday, March 5, 2015, the U.N. health agency said the study will be focused in Basse Guinee, the region that currently has the most Ebola cases in the country. (AP Photo/Youssouf Bah, File)
A man gets vaccinated on March 10, 2015 at a health center in Conakry during the first clinical trials of the VSV-EBOV vaccine against the Ebola virus. The World Health Organization (WHO) said on March 5 that clinical trials launched on March 7 in Guinea marked the last step before the vaccine is available on the market. AFP PHOTO / CELLOU BINANI (Photo credit should read CELLOU BINANI/AFP/Getty Images)
A dose of the VSV-EBOV vaccine against the Ebola virus sits on March 10, 2015 at a health center in Conakry during its first clinical trial on humans. The World Health Organization (WHO) said on March 5 that clinical trials launched on March 7 in Guinea marked the last step before the vaccine is available on the market. AFP PHOTO / CELLOU BINANI (Photo credit should read CELLOU BINANI/AFP/Getty Images)
A woman gets vaccinated on March 10, 2015 at a health center in Conakry during the first clinical trials of the VSV-EBOV vaccine against the Ebola virus. The World Health Organization (WHO) said on March 5 that clinical trials launched on March 7 in Guinea marked the last step before the vaccine is available on the market. AFP PHOTO / CELLOU BINANI (Photo credit should read CELLOU BINANI/AFP/Getty Images)
A man gets vaccinated on March 10, 2015 at a health center in Conakry during the first clinical trials of the VSV-EBOV vaccine against the Ebola virus. The World Health Organization (WHO) said on March 5 that clinical trials launched on March 7 in Guinea marked the last step before the vaccine is available on the market. AFP PHOTO / CELLOU BINANI (Photo credit should read CELLOU BINANI/AFP/Getty Images)
A health worker, left, injects a man in his arm with an Ebola vaccine in Conakry, Guinea, March 7, 2015. The World Health Organization will start large-scale testing of an experimental Ebola vaccine in Guinea on Saturday to see how effective it might be in preventing future outbreaks of the deadly virus. The West African nations of Sierra Leone, Liberia and Guinea have been hardest hit in the yearlong Ebola outbreak, which is estimated to have left more than 9,800 people dead. (AP Photo/ Youssouf Bah)
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"We believe that the world is on the verge of an efficacious Ebola vaccine," WHO vaccine expert Marie Paule Kieny told reporters in a briefing from Geneva.

The vaccine could now be used to help end the worst recorded outbreak of Ebola, which has killed more than 11,200 people in West Africa since it began in December 2013.

WHO Director-General Margaret Chan said the results, published online in the medical journal The Lancet, would "change the management of the current Ebola outbreak and future outbreaks".

The Gavi Alliance, which buys vaccines in bulk for poor countries who struggle to afford them, immediately said it would back an Ebola shot once it is approved.

"These communities need an effective vaccine sooner rather than later," Gavi's chief executive Seth Berkley said. "We need to be ready to act wherever the virus is a threat."

This and other vaccine trials were fast-tracked with huge international effort as researchers raced to test potential therapies and vaccines while the virus was still circulating.

"It was a race against time and the trial had to be implemented under the most challenging circumstances," said John-Arne Røttingen of Norway's Institute of Public Health, chair of the trial's steering group.


(Data Curated by healthgrove.com)

"RING VACCINATION"

The Guinea trial began on March 23 to evaluate the effectiveness and safety of a single dose of VSV-ZEBOV using a so-called "ring vaccination" strategy, where close contacts of a person diagnosed with Ebola are immunized - either immediately, or at a later date.

As data began to emerge showing the very high protection rates in those vaccinated immediately, however, researchers decided on July 26 that they would no longer use the "delayed" strategy, since it was becoming clear that making people wait involved unethical and unnecessary risk.

The trial is now being continued, with all participants receiving the vaccine immediately, and will be extended to include 13- to 17-year-olds and possibly also 6- to 12-year-old children, the WHO said.

Jeremy Farrar, a leading infectious disease specialist and director of the Wellcome Trust, said the trial "dared to use a highly innovative and pragmatic design, which allowed the team in Guinea to assess this vaccine in the middle of an epidemic".

"Our hope is that this vaccine will now help bring this epidemic to an end and be available for the inevitable future Ebola epidemics," his statement said.

More from last year's outbreak:

49 PHOTOS
Liberia Ebola - vaccine - last updated 7/1/2015
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Vaccine success holds hope for end to deadly scourge of Ebola
Health workers leave after they took a blood specimen from a child to test for the Ebola virus in a area were a 17-year old boy died from the virus on the outskirts of Monrovia, Liberia, Tuesday, June 30, 2015. Liberian authorities on Tuesday quarantined an area where the corpse was found, sparking fears this West African country could face another outbreak of the disease nearly two months after being declared Ebola-free. (AP Photo/ Abbas Dulleh)
Health workers wash their hands after taking a blood specimen from a child to test for the Ebola virus in an area where a 17-year old boy died from the virus on the outskirts of Monrovia, Liberia, Tuesday, June 30, 2015. Liberian authorities on Tuesday quarantined the area where the corpse of the boy was found, sparking fears this West African country could face another outbreak of the disease nearly two months after being declared Ebola-free. (AP Photo/ Abbas Dulleh)
Health workers take a blood specimen from a child to test for the Ebola virus in a area were a 17-year old boy died from the virus on the outskirts of Monrovia, Liberia, Tuesday, June 30, 2015. Liberian authorities on Tuesday quarantined an area where the corpse of the boy was found, sparking fears this West African country could face another outbreak of the disease nearly two months after being declared Ebola-free. (AP Photo/ Abbas Dulleh)
A woman holds a placard as she and others celebrate Liberia being an Ebola free nation in Monrovia, Liberia, Monday, May 11, 2015. Liberians are gathering in the streets of the capital to celebrate the end of the Ebola epidemic in this West African country. Monday's festivities come after the World Health Organization declared over the weekend that Liberia was finally Ebola-free. (AP Photo/ Abbas Dulleh)
People display a representation of the Liberian flag as they celebrate Liberia being an Ebola free nation in Monrovia, Liberia, Monday, May 11, 2015. Liberians are gathering in the streets of the capital to celebrate the end of the Ebola epidemic in this West African country. Monday's festivities come after the World Health Organization declared over the weekend that Liberia was finally Ebola-free. (AP Photo/ Abbas Dulleh)
A woman smiles as she celebrates Liberia being an Ebola-free nation in Monrovia, Liberia, Saturday, May 9, 2015. Liberia is now free of Ebola after going 42 days — twice the maximum incubation period for the deadly disease — without any new cases, the World Health Organization announced on Saturday.(AP Photo/ Abbas Dulleh)
In this photo taken on Friday, May 8, 2015, Mercy Kennedy, left, sits with her caregiver Martu Weefor, right, after school at her home in Monrovia, Liberia. On the day Mercy Kennedy lost her mother to Ebola, it was hard to imagine a time Liberia would be free of one of the world’s deadliest viruses. It had swept through the 9-year-old’s neighborhood, killing people house by house. Now seven months later, Liberia on Saturday officially marked the end of the epidemic that claimed more than 4,700 lives here, and Mercy is thriving in the care of a family friend not far from where she used to live. (AP Photo/ Abbas Dulleh)
MONROVIA, LIBERIA - FEBRUARY 02: A nurse takes a blood sample from Emmanuel Lansana, 43, the first person to take part in the Ebola vaccine study being conducted at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Lansana, a physician's assistant, was the first of 12 people given injections on the first day, out of a planned 27,000 people in the Monrovia area. The clinical research study is being conducted jointly by the U.S. National Institutes of Health (NIH), and the Liberian Ministry of Health. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: A nurse speaks with a volunteer for the Ebola vaccine trials, which were launched at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Twelve people were given injections on the first day, out of a planned 27,000 people in the Monrovia area. The clinical research study is being conducted jointly by the U.S. National Institutes of Health (NIH), and the Liberian Ministry of Health. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
People walk near a sign calling for volunteers for an Ebola vaccine study at Redemption Hospital in New Kru Town, a suburb of Monrovia, on February 2, 2015. The first large-scale trials of two Ebola vaccines were due to begin in Liberia on February 2, the partnership conducting the research said. The vaccines contain harmless fragments of the virus that trigger an immune response, according to the Partnership for Research on Ebola Vaccines in Liberia (PREVAIL), a collaboration between the United States and Liberia. AFP PHOTO / ZOOM DOSSO (Photo credit should read ZOOM DOSSO/AFP/Getty Images)
A woman, right, is injected by a health care worker, left, as she takes part in a Ebola virus vaccine trial at one of the largest hospital's Redemption hospital in Monrovia, Liberia, Monday, Feb. 2, 2015. A large-scale human trial of two potential Ebola vaccines got under way in Liberia's capital Monday, part of a global effort to prevent a repeat of the epidemic that has now claimed nearly 9,000 lives in West Africa. (AP Photo/ Abbas Dulleh)
MONROVIA, LIBERIA - FEBRUARY 02: Mothers bring their sick children for treatment at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Life is slowly returning to normal for many Liberians, and most hospitals and clinics have re-opened as the Ebola epidemic wanes. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: People await treatment in the outpatient lounge of Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Most hospitals and clinics have re-opened, as the Ebola epidemic wanes. The virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: People await outpatient treatment at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Most hospitals and clinics have re-opened, as the Ebola epidemic wanes. The virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: Health workers in protective clothing await patients in the outpatient lounge of Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Most hospitals and clinics have re-opened, as the Ebola epidemic wanes. The virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: A placard with information on identifying Ebola symptoms lies in the outpatient waiting room of Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Most hospitals and clinics have re-opened, as the Ebola epidemic wanes. The virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: A doctor displays Ebola vaccines to be given in the vaccine trials which were launched at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Twelve people given injections on the first day, out of a planned 27,000 people in the Monrovia area. The clinical research study is being conducted jointly by the U.S. National Institutes of Health (NIH), and the Liberian Ministry of Health. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: Emmanuel Lansana, 43, takes part in a briefing before becoming the first person to be injected in the Ebola vaccine trials, which were launched at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Lansana, a physician's assistant, was the first of 12 people given injections on the first day, out of a planned 27,000 people in the Monrovia area. The clinical research study is being conducted jointly by the U.S. National Institutes of Health (NIH), and the Liberian Ministry of Health. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: Health workers in protective clothing speak with new arrivals in the outpatient waiting room of Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Most hospitals and clinics have re-opened, as the Ebola epidemic wanes. The virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: Dr. Mike Montello, research director at the U.S. National Institutes of Health, prepares the first batch of Ebola vaccines to be given in the Ebola vaccine trials, which were launched at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Twelve people were given injections on the first day, out of a planned 27,000 people in the Monrovia area. The clinical research study is being conducted jointly by the U.S. National Institutes of Health (NIH), and the Liberian Ministry of Health. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: A nurse takes a blood sample from Emmanuel Lansana, 43, the first person to take part in the Ebola vaccine study being conducted at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Lansana, a physician's assistant, was the first of 12 people given injections on the first day, out of a planned 27,000 people in the Monrovia area. The clinical research study is being conducted jointly by the U.S. National Institutes of Health (NIH), and the Liberian Ministry of Health. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: A nurse administers an injection to Emmanuel Lansana, 43, the first person to take part in the Ebola vaccine trials being conducted at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Lansana was the first of 12 people given injections, out of a planned 27,000 people in the Monrovia area. The clinical research study is being conducted jointly by the U.S. National Institutes of Health (NIH), and the Liberian Ministry of Health. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: Emmanuel Lansana, 43, takes part in a briefing before becoming the first person to be injected in the Ebola vaccine trials, which were launched at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Lansana, a physician's assistant, was the first of 12 people given injections on the first day, out of a planned 27,000 people in the Monrovia area. The clinical research study is being conducted jointly by the U.S. National Institutes of Health (NIH), and the Liberian Ministry of Health. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: A Liberian pharmacist prepares an Ebola vaccine to be given in the vaccine trials, which were launched at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Twelve people were given injections on the first day, out of a planned 27,000 people in the Monrovia area. The clinical research study is being conducted jointly by the U.S. National Institutes of Health (NIH), and the Liberian Ministry of Health. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
MONROVIA, LIBERIA - FEBRUARY 02: A nurse speaks with a volunteer for the Ebola vaccine trials, which were launched at Redemption Hospital, formerly an Ebola holding center, on February 2, 2015 in Monrovia, Liberia. Twelve people were given injections on the first day, out of a planned 27,000 people in the Monrovia area. The clinical research study is being conducted jointly by the U.S. National Institutes of Health (NIH), and the Liberian Ministry of Health. The Ebola epidemic virus has killed at least 3,700 people in Liberia alone, the most of any country, and nearly 9,000 across in West Africa. (Photo by John Moore/Getty Images)
In this photo taken Saturday, Nov. 8, 2014, health Care workers load the body of a dead woman suspected of dying from Ebola, onto the back of a truck in Jene-Wonde, Liberia. A schoolteacher brought his sick daughter from Liberia’s capital to this small town of 300 people. Soon he was dead along with his entire family, all buried in the forest nearby. (AP Photo/ Wade Williams)
In this photo taken Saturday, Nov. 8, 2014, a woman reacts, rear, as Health Care workers load the body of a family member suspected of dying from Ebola, onto the back of a truck in Jene-Wonde, Liberia. A schoolteacher brought his sick daughter from Liberia’s capital to this small town of 300 people. Soon he was dead along with his entire family, all buried in the forest nearby. (AP Photo/ Wade Williams)
Cpl. Zachary Wicker puts on germ-resistant gear in Fort Bliss, Texas, Tuesday, Oct. 14, 2014. About 500 Fort Bliss soldiers are training to use germ-proof suits and other equipment ahead of a deployment to West Africa where they'll participate in a U.S. military mission in areas affected by the Ebola outbreak. (AP Photo/Juan Carlos Llorca)
Social Commentator Alfred Sirleaf, gives comment on current events in Liberia including the deadly Ebola virus by speaking and writhing them down on a blackboard in Monrovia, Liberia, Thursday, July 31, 2014. The worst recorded Ebola outbreak in history surpassed 700 deaths in West Africa as the World Health Organization on Thursday announced dozens of new fatalities. (AP Photo/Jonathan Paye-Layleh)
An employee of the Monrovia City Corporation sprays disinfectant inside a government building in a bid to prevent the spread of the deadly Ebola virus, in the city of Monrovia, Liberia, Friday, Aug. 1, 2014. U.S. health officials warned Americans not to travel to the three West African countries hit by the worst recorded Ebola outbreak in history. The travel advisory issued Thursday applies to nonessential travel to Guinea, Liberia and Sierra Leone, where the deadly disease has killed more than 700 people this year. (AP Photo/Abbas Dulleh)
A man's temperature is measured before he is allowed into a business center, as fear of the deadly Ebola virus spreads through the city of Monrovia, Liberia, Saturday, Aug. 9, 2014. Over the decades, Ebola cases have been confirmed in 10 African countries, including Congo where the disease was first reported in 1976. But until this year, Ebola had never come to West Africa. (AP Photo/Abbas Dulleh)
The body of a man, background, suspected of dying from the Ebola virus lies on the ground, as health workers, right, spray themselves with disinfectant, in the capital city of Monrovia, Liberia, Tuesday, Aug. 12, 2014. The World Health Organization declared it’s ethical to use untested drugs and vaccines in the ongoing Ebola outbreak in West Africa although the tiny supply of one experimental drug handed out to three people has been depleted and it could be many months until more is available. (AP Photo/Abbas Dulleh)
A Liberian woman holds up a pamphlet with guidance on how to prevent the Ebola virus from spreading, in the city of Monrovia, Liberia, Thursday, Aug. 14, 2014. Liberian officials faced a difficult choice Thursday: deciding which handful of Ebola patients will receive an experimental drug that could prove life-saving, ineffective or even harmful. (AP Photo/Abbas Dulleh)
Health workers are handed personal protective gear by a team leader, right, before collecting the bodies of the deceased from streets in Monrovia, Liberia, Saturday, Aug. 16, 2014. New figures released by the World Health Organization showed that Liberia has recorded more Ebola deaths — 413 — than any of the other affected countries. (AP Photo/Abbas Dulleh)
Health workers wearing protective gear go to remove the body of a person who is believed to have died after contracting the Ebola virus in the city of Monrovia, Liberia, Saturday, Aug. 16, 2014. New figures released by the World Health Organization showed that Liberia has recorded more Ebola deaths — 413 — than any of the other affected countries. (AP Photo/Abbas Dulleh)
Liberia security forces patrol in the West Point area, as the government clamps down on the movement of people to prevent the spread of the Ebola virus in Monrovia, Liberia, Wednesday, Aug. 20, 2014. Security forces deployed Wednesday to enforce a quarantine around a slum in the Liberian capital, stepping up the government’s fight to stop the spread of Ebola and unnerving residents. (AP Photo/Abbas Dulleh)
Liberian soldiers keep order at a food distribution center, Thursday, Aug. 21, 2014, at the West Point area, one of the places where the Ebola virus has claimed lives, in Monrovia, Liberia. Calm returned Thursday to a slum in the Liberian capital that was sealed off in the government's attempt to halt the spread of Ebola, a day after clashes erupted between residents and security forces, but now the tens of thousands of residents worried about getting food. (AP Photo/Abbas Dulleh)
Liberian health workers spray disinfectant outside a house before entering and removing the body of a man that they believe died from the Ebola virus in Monrovia, Liberia, Friday, Aug. 29, 2014. The Ebola outbreak in West Africa eventually could exceed 20,000 cases, more than six times as many as are now known, the World Health Organization said Thursday. A new plan released by the U.N. health agency to stop Ebola also assumes that the actual number of cases in many hard-hit areas may be two to four times higher than currently reported.(AP Photo/Abbas Dulleh)
Thousands of people take to a street outside of West Point slum in Monrovia, Liberia, Saturday, Aug. 30, 2014. Crowds cheer and celebrate in the streets after Liberian authorities reopened a slum where tens of thousands of people were barricaded amid the country’s Ebola outbreak. The slum of 50,000 people in Liberia's capital was sealed off more than a week ago, sparking unrest and leaving many without access to food or safe water. (AP Photo/Abbas Dulleh)
Doctor and nurse wearing protective gear take part in a drill with a dummy to demonstrate the procedures of transporting an Ebola patient,in Hong Kong Tuesday, Sept. 2, 2014. An Ebola outbreak in West Africa has killed more than 1,500 people in Guinea, Liberia, Sierra Leone and Nigeria. The university student is Senegal's first case of the dreaded disease. (AP Photo/Tyrone Siu, Pool)
Health workers load the body of an amputee suspected of dying from the Ebola virus during the rain on the back of a truck, in a busy street in Monrovia, Liberia, Tuesday, Sept. 2, 2014. Food in countries hit by Ebola is getting more expensive and will become scarcer because many farmers won't be able to access fields, a U.N. food agency warned Tuesday. An Ebola outbreak in West Africa has killed more than 1,500 people, and authorities have cordoned off entire towns in an effort to halt the virus' spread. (AP Photo/Abbas Dulleh)
Health worker's spray each other with disinfectant chemicals as they worked with a suspected Ebola virus death in Monrovia, Liberia, Thursday, Sept. 4, 2014. As West Africa struggles to contain the biggest ever outbreak of Ebola, some experts say an unusual but simple treatment might help: the blood of survivors. The evidence is mixed for using infection-fighting antibodies from survivors' blood for Ebola, but without any licensed drugs or vaccines for the deadly disease, some say it's worth a shot. (AP Photo/Abbas Dulleh)
Health workers carry the body of a woman that they suspect died from the Ebola virus, in an area known as Clara Town in Monrovia, Liberia, Wednesday, Sept. 10, 2014. A surge in Ebola infections in Liberia is driving a spiraling outbreak in West Africa that is increasingly putting health workers at risk as they struggle to treat an overwhelming number of patients. A higher proportion of health workers has been infected in this outbreak than in any previous one. (AP Photo/Abbas Dulleh)
A Nigerian health official wearing a protective suit waits to screen passengers at the arrivals hall of Murtala Muhammed International Airport in Lagos, Nigeria, Monday, Aug. 4, 2014. Nigerian authorities on Monday confirmed a second case of Ebola in Africa's most populous country, an alarming setback as officials across the region battle to stop the spread of a disease that has killed more than 700 people. (AP Photo/Sunday Alamba)
Bystanders react as they listen to a street preacher calling on people to raise their hands and "Wave Ebola Bye Bye" in Monrovia, Liberia, Saturday Sept. 27, 2014. Six months into the world’s worst-ever Ebola outbreak in West Africa, the region is desperate to receive enough aid to fight the disease. (AP Photo/Jerome Delay)
Nowa Paye, 9, is taken to an ambulance after showing signs of the Ebola infection in the village of Freeman Reserve, about 30 miles north of Monrovia, Liberia,Tuesday Sept. 30, 2014. Three members of District 13 ambulance service traveled to the village to pickup six suspected Ebola sufferers that had been quarantined by villagers. Aid donations are still inadequate, as the international community tries to increase the ability to care for the spiraling number of people infected with the disease which has hit Liberia the hardest. (AP Photo/Jerome Delay)
Army Stf. Sgt. Samuel Hines, left, helps Cpl. Zachary Wicker tape gloves to his uniform in Fort Bliss, Texas, Tuesday, Oct. 14, 2014. About 500 Fort Bliss soldiers are preparing for deployment to West Africa where they will provide support in a military effort to contain the Ebola outbreak. (AP Photo/Juan Carlos Llorca)
Army Stf. Sgt. Samuel Hines, left, helps Cpl. Zachary Wicker tape gloves to his uniform in Fort Bliss, Texas, Tuesday, Oct. 14, 2014. About 500 Fort Bliss soldiers are preparing for deployment to West Africa where they will provide support in a military effort to contain the Ebola outbreak. (AP Photo/Juan Carlos Llorca)
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The medical charity Doctors without Borders (MSF), which has led the fight against Ebola in West Africa, called for VSV-ZEBOV to be rolled out to the other centers of the outbreak, Liberia and Sierra Leone, where it says it could break chains of transmission and protect front-line health workers.

VSV-ZEBOV was originally developed by Canada's public health agency before being licensed to NewLink Genetics, which then signed a deal handing Merck the responsibility to research, develop, manufacture and distribute it.

The success of the Guinea trial is a big relief for researchers, many of whom feared a sharp decline in cases this year would scupper their hopes of proving a vaccine could work.

Another major trial in Liberia, which had aimed to recruit some 28,000 subjects, had to stop enrolling after only reaching its mid-stage target of 1,500 participants. Plans for testing in Sierra Leone were also scaled back. That left the study in Guinea, where Ebola is still infecting new victims, as the only real hope for demonstrating the efficacy of a vaccine.


(Data Curated by healthgrove.com)


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