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Human Trials for Two New Ebola Vaccines Just Began in Liberia

As the rate of new Ebola cases in West Africa drops to its lowest point since June, 600 volunteers in Liberia are beginning trials for two potential vaccines.
Photo via Flickr

For the first time since June of last year, Guinea, Liberia, and Sierra Leone reported fewer than 100 confirmed cases of Ebola infection combined last week. While the epidemic enters what the World Health Organization is calling the "second phase" of the outbreak — trending toward zero cases — research continues to progress into how to prevent the disease.

The first set of large-scale vaccine trials began today in Liberia's capital city of Monrovia. After being transported into the country with tight security, two experimental vaccines developed separately by the US National Institutes of Health (NIH) and Canadian health officials will be studied in the trials. Scientists say they will administer the vaccines to as many as 600 volunteers, with the potential of eventually scaling up to 27,000 people. Today, 12 individuals were set to receive an injection.


National Institutes of Allergy and Infectious Disease Director Anthony Fauci told the Associated Press that in the first round of trials both vaccines exhibited promise in fighting off the virus, which has claimed more than 8,800 lives and infected upwards of 22,000 people in the three countries since it appeared in the forest region of Guinea more than a year ago.

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The vaccine administered today consists of an Ebola virus strain. While several strains of the disease have been identified since its initial discover nearly 40 years ago, there is no proven vaccine or cure.

As the first volunteer was vaccinated on Monday, scientists acknowledged to the BBC that community support for the trial was crucial. Local healthcare workers will be tasked with keeping tabs on those who have received the shots. Scientists were also tasked with ensuring the public that the process was safe.

"There is no danger because the piece of the Zaire strain that has been put into the vaccine is a weak strain, and it cannot and will not cause Ebola," Stephen Kennedy, the senior Liberian scientist on the trial, told the BBC. "So it is impossible that any one of the volunteers will contract Ebola from the vaccine."

While researchers push forward with the vaccine trials in Liberia, the most recent report from WHO indicates that the number of cases has dropped to single digits in the country. With this shift, efforts in the three countries are pivoting away from slowing transmission and toward ending the epidemic. But the decline in cases may actually hinder attempts to develop a treatment for Ebola.


A clinical trial in Monrovia for a drug developed by Chimerix was nixed Friday, reportedly due the drop in infections. Chimerix CEO Dr. M. Michelle Berry told the New York Times that it would not be possible to move forward with the trial without a sufficient amount of patients. Chimerix had sent doses for 140 patients to the country for the test that began on January 2, but fewer than than 10 people had received treatment. Similarly, a study into plasma of Ebola survivors is looking to relocate from Liberia to Sierra Leone, where Ebola infection has dropped but remains more common.

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As the course of the current outbreak wanes, the best shot at seeing results from a vaccine trial may be in Guinea. Liberia and Sierra Leone have both seen large flare-ups and spikes in transmission since the virus crossed their borders in March and May respectively. However, in Guinea, where the disease first made its jump from animal to human in December 2013, the spread of Ebola has proved less extreme but more consistent.

At a high-level meeting earlier this month on Ebola vaccines, WHO Director-General Margaret Chan said that the industry was moving quickly in developing potential solutions.

"What you are doing is unprecedented," she said. "Compressing into a matter of months work that normally takes 2 to 4 years, yet with no compromise of international standards of safety and efficacy,"

Follow Kayla Ruble on Twitter: @RubleKB

Photo via Flickr