A clinical trial of an Ebola vaccine has been suspended after four patients complained of joint pains in their limbs, the University of Geneva hospital said Thursday.
"They are all fine and being monitored regularly by the medical team leading the study," The Guardian quoted the hospital as saying in a statement.
The trials of the vaccine, developed by pharmaceutical firms Merck and NewLink, will now begin Jan 5.
The decision to suspend the trials comes as health officials in Sierra Leone discovered scores of bodies in a remote diamond-mining area, raising fears of a spike in the number of unreported deaths.
The World Health Organisation said it uncovered a "grim scene" in Sierra Leone's Kono district.
Sierra Leone has now overtaken Liberia as the country with the highest number of Ebola cases in west Africa, with 7,897 cases since the beginning of the outbreak.
The Ebola epidemic has killed more than 6,000 people in west Africa.