Success of an experimental ebola vaccine in the first phase of testing in volunteers

While the ebola is still claiming victims in West Africa, the first human trials with one of the more advanced experimental vaccines offer promising data. This immunization has proved safe in healthy volunteers and has managed to develop an immune response against the virus.

The aim of the test, known as phase 1, was to analyze whether the treatment produced side effects in 20 healthy volunteers. But the preliminary results of the test, which is published today in the New England Journal of Medicine, also indicate that all the participants have developed antibodies against the ebola and other also had an increased immune response. It is something similar to what has already been observed in monkeys, to which this vaccine succeeded in protecting to 100% of the contagion. Now it remains to be seen whether the immune response in the registered volunteers is enough to slow the spread in humans.

The tested vaccine contains DNA variants of the Zaire and Sudan of the virus. The first is the responsible for the current outbreak in West Africa, in which have already been registered 15,935 cases and 5,689 deaths, according to the latest data from the World Health Organization (WHO). The treatment has been developed by the National Institutes of Health (NIH) in the USA and the company Okairos, acquired by GlaxoSmithKline. This vaccine uses a chimpanzee virus disabled to carry those fragments of viral DNA to the agency and that this learn how to recognize and fight one of the protein that surrounds the ebola virus.

"You might say that this vaccine has passed the first phase of human trials with success," says Rafael Delgado, University Hospital October 12 and a member of the scientific committee that is advising the Government during the present crisis of Ebola. However, it is interim results, warns. "By now there is no demonstration of effectiveness, but we do know that it is reasonably safe and that you can pass to the phase 2 and 3 to test its effectiveness in individuals at risk of infection," he adds.

The following test phases of this vaccine would be carried out in Liberia, one of the countries most affected by the current outbreak. The responsible of the vaccine are already negotiating with the Government of this country to design these clinical trials, reports the NIH. They would prove the efficacy of this vaccine compared with other candidates. First we will have to collect more data from this trial, which began in September and has a duration of 48 weeks, and the other that are in progress. It is not expected that an announcement of a new phase of testing until the beginning of the next year, say the NIH.

The necessary clinical trials to test the effectiveness of the vaccines will compel to take "difficult decisions," warns Daniel Bausch, medical specialist in tropical diseases of the Tulane University in the US, in an editorial published next to the new study results. He wondered if you can perform clinical trials "classics" in which a group receives a placebo instead of a candidate for a vaccine or if, on the contrary, it is comparing the two vaccine candidates more advanced in only two groups, which would make it very difficult find out its true effectiveness. Although this is a controversial option, experts who have recognized that the use of placebo in a group would know more quickly if a vaccine is effective, according to the Guardian. "There is still discussion about this issue and has not taken a firm decision," says Slim.