GENEVA — The hunt for an Ebola vaccine will produce data soon about whether two experimental vaccines are safe and could lead to larger medical trials in West Africa by January, a top World Health Organization official said Tuesday.

Dr Marie Paule Kieny, an assistant director general for WHO, said clinical trials either planned or underway in Europe, Africa and the U.S. are expected to produce preliminary safety data by December. In the meantime, she said, governments are pushing for immediate “real-world use” of an approved Ebola vaccine.

She told reporters Tuesday in Geneva there are two leading candidates for a vaccine. If the vaccines are deemed safe, tens of thousands of doses will be used in trials in West Africa beginning in January to test their effectiveness, she said.

One of those vaccines, developed by the U.S. National Institutes of Health and GlaxoSmithKline from a modified chimpanzee cold virus and an Ebola protein, is in clinical trials in the U.K. and in Mali. It will be used in clinical trials in Lausanne, Switzerland, by the start of February.

The second front-runner, developed by the Public Health Agency of Canada and known as VSV-EBOV, has been sent to the U.S. Walter Reed Army Institute of Research in Maryland for testing on healthy volunteers, with results expected by December. The next stage would be to test it more broadly, including among those directly handling Ebola cases in West Africa.

Canada has donated 800 vials of the experimental vaccine to WHO but the shipment was delayed by a Lufthansa pilots strike. It is now expected to arrive in Switzerland on Wednesday for testing coordinated by the U.N. health agency among volunteers at the University Hospital of Geneva, and volunteers in Hamburg, Germany, and in Gabon and Kenya, Kieny said.