“The best case scenario would be three months. And we should certainly be able to do this [declare that the outbreak in Sierra Leone is over] by the end of September," Bruce Aylward said.
"The question is how many transmission chains are we dealing with,” the official said. “Right now we can only see in the last three weeks incubation period they've only had transmission chains in two districts. And in both of those districts very limited number of transmission chains.”
The current outbreak of the Ebola virus started in December 2013, spreading into Liberia, Sierra Leone, Nigeria, Senegal and Mali in 2014.
Sierra Leone is one of the worst-affected countries in the region. Over 12,400 cases of Ebola have been reported in the country. Almost 4,000 people died from the disease, according to WHO.
On Saturday, WHO announced that Liberia was free from Ebola, as 42 days had passed since the last laboratory-confirmed case was buried on March 28.