Health workers in the Democratic Republic of Congo are to begin an immunisation campaign in an attempt to halt the spread of the deadly Ebola virus.
The experimental vaccine proved effective when used in limited trials during the outbreak in West Africa in 2014-16.
At least 25 people are believed to have died in the current outbreak.
Health workers will be among the first to receive the vaccine on Monday.
It is an infectious illness that causes internal bleeding and often proves fatal.
It can spread rapidly through contact with small amounts of bodily fluid, and its early flu-like symptoms are not always obvious.
More than 11,300 people died in the earlier outbreak in 2014-16.
At least 45 cases of Ebola have been reported so far, including three health workers.
The virus has already spread from rural areas to the north-western city of Mbandaka, a major transport hub on the River Congo, where at least four cases have been confirmed.
This has sparked fears that the outbreak could reach the capital, Kinshasa, as well as neighbouring countries.
However, the World Health Organization (WHO) has said it has "strong reason to believe that the outbreak can be brought under control".
At an emergency meeting, on Friday WHO experts said that “the conitions for a Public Health Emergency of International Concern (PHEIC) have not yet currently been met”.