The world is on the verge of developing an effective Ebola vaccine, the World Health Organization announced Friday.

Trials of a new vaccine, conducted by an independent body of international experts, protected 100 percent of individuals tested in Guinea, showing that it is "highly effective against Ebola," WHO said in a news release published on its website. 

The new vaccine, called VSV-EBOV, "might be highly efficacious and safe in preventing Ebola virus disease, and is most likely effective at the population level when delivered during an Ebola virus disease outbreak via a ring vaccination strategy," the authors of the study wrote.

The ring vaccination strategy used in the trial is based on the smallpox eradication strategy, in which everyone who has come into contact with an infected person gets vaccinated, according to Dr. John Arne Rottingen, head of the Study Steering Group and also the director for the Division of Infectious Disease Control of the Norwegian Institute of Public Health.

"The premise is that by vaccinating all people who have come into contact with an infected person you create a protective 'ring' and stop the virus from spreading further," Rottingen explained. "This strategy has helped us to follow the dispersed epidemic in Guinea, and will provide a way to continue this as a public health intervention in trial mode."

The Ebola vaccine ring strategy trial for affected communities in Guinea started on March 23 and involved 100 Ebola patients. More than 4,000 people who have come into close contact with these patients have participated.

Because of the effective results, randomization for the trial was dropped on July 26, and everyone at risk was immediately given the vaccine. This also allowed the researchers to gather data faster in the hope of getting a license for the vaccine sooner.

The Ebola vaccine has also been proven safe, allowing the trial to test the vaccine on younger patients from the age brackets 6 to 12 and 13 to 17. The vaccine will also be tested on frontline workers.

"I thought the only way to be successful would be to follow the epidemic and try to vaccinate in high-risk individuals," said Rottingen, adding that the Ebola vaccine trial in Guinea "has been more successful than we almost could have hoped for," according to The New York Times. 

Dr. Margaret Chan, director general of WHO, called the new Ebola vaccine "an extremely promising development."

"The credit goes to the Guinean Government, the people living in the communities and our partners in this project. An effective vaccine will be another very important tool for both current and future Ebola outbreaks," said Chan, according to the WHO news release.

While the vaccine showed very promising results, more studies are needed particularly to test it for "herd immunity," which happens when a portion of a population has developed a general immunity to the virus such that individuals who have not developed an immunity to it are protected.

The national regulatory authority and ethics review committee of Guinea have approved the continuation of the trials in the country.

The initial results of the study were published in the July 31 issue of the British medical journal The Lancet.

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