The decision will be taken by WHO's Strategy Advisory Group of Experts (SAGE) based on the outcome of trials which are currently underway in Africa.
"Vaccine introduction is by no means a given and will depend on the results of clinical trials and recommendations from WHO's Strategy Advisory Group of Experts (SAGE) on vaccines and immunisation," WHO spokesman Christian Lindmeier said.
"The earliest that the SAGE is expected to make recommendation on a wide-scale introduction is August. Decisions on whether or not to introduce the vaccine will be made by the respective ministries of health of countries," he added.
Third phase clinical trials for the two vaccines - developed by GlaxoSmithKline (GSK) and Merck - have begun on West Africa, the epicentre of the Ebola crisis.
The WHO said in a statement yesterday that the number of people killed by Ebola has reached 9,589, while over 23,000 people have been infected with the deadly virus.
SAGE, which was established in 1999, is the principal advisory group to WHO for vaccines and immunisation, including vaccine-preventable diseases.
It also advises the WHO on immunisation and its linkages with other human interventions, overall global strategies and research and development.

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