Ebola vaccines move closer to ultimate test

The race to develop Ebola vaccines will soon enter a new phase that may bring answers to the most important question: Do they actually work? In as little as 4 weeks, tests could begin in West Africa in people at risk of contracting Ebola with one of two vaccines that have moved forward at an unprecedented pace, said Marie-Paule Kieny, an assistant director-general at the World Health Organization (WHO), at a press conference today in Geneva, Switzerland. But a new issue is complicating the studies. The number of new Ebola cases has declined unexpectedly fast in recent months, especially in Liberia. That’s great news, but it will make it harder to show that a vaccine works, because the studies need a minimum number of new infections to prove that it offers protection from the disease. So far, so-called phase I tests have given experimental Ebola vaccines to healthy volunteers not at risk...