LONDON -- Swiss researchers have suspended the testing of one of the leading Ebola vaccine candidates after some volunteers reported unexpected side effects.

In a statement issued on Thursday, the Hopitaux Universitaires de Geneve said the trial had been suspended "as a precautionary measure." The study involving 59 people began in November.

Researchers reported four cases of mild joint pain in the hands and feet in people who got the shot 10 to 15 days earlier. Officials will stop giving the vaccine next week to get more data and liaise with others who are testing the vaccine in the U.S., Canada, Germany and Gabon.

Get Breaking News Delivered to Your Inbox

The vaccine was developed by the Canadian government and is licensed to two U.S. companies, NewLink and Merck. The trial is scheduled to resume in January in Geneva.

This is just one of several experimental vaccines currently being tested worldwide to combat the deadly Ebola outbreak. The U.S. National Institutes of Health reported last month that a vaccine being tested in Bethesda, Maryland, appeared safe in an early study and elicited a promising immune system response.

Since the outbreak began earlier this year, Ebola has infected more than 17,800 people and killed more than 6,300, mostly in Liberia, Guinea and Sierra Leone.