ZURICH—An Ebola vaccine developed by Canada’s public health agency will go into late-stage human testing Saturday in Guinea, one of the three West African countries that has been hard hit by the disease, the World Health Organization said Thursday.

The United Nations’ health agency said Thursday that Phase III trials of the rVSV-EBOV vaccine would begin in Basse Guinée, the region of Guinea that currently has the highest number of Ebola cases. Phase III trials are the last stage of human testing before drugs are submitted...