UNITED NATIONS, Rajab 23, 1436, May 12, 2015, SPA -- The World Health Organization (WHO) said Tuesday that vaccine trials will most likely fail to provide enough useful data on how well they protect people against Ebola. Liberia was declared free from Ebola Saturday. Guinea reported seven cases in the week of May 4 to May 10, while Sierra Leone had two, Dr. Marie-Paule Kieny, WHO assistant director-general for health systems and innovation, told reporters in Geneva. “The best news is we are going to zero cases; there is absolutely no doubt about that,” Kieny said. But two experimental Ebola vaccines being tested on volunteers may not yield sufficient data on efficacy as case numbers fall, Kieny said. “It is not clear whether it will be possible to have even a hint of efficacy from these two vaccines. To have efficacy we must see if people are actually protected, as the number of cases is going down it is not clear whether there will be a strong robust answer to this question at the end of epidemic,” Kieny said. Two drugs also are being tested and Kieny said that the hope is they will produce some limited results on efficacy. --SPA 17:56 LOCAL TIME 14:56 GMT www.spa.gov.sa/w