MADRID (AP) — The World Health Organization declared it’s ethical to use untested drugs and vaccines in the ongoing Ebola outbreak in West Africa, although the tiny supply of one experimental treatment has been depleted and it could be many months until more is available.

The last of the drug is on its way to Liberia for two stricken doctors, according to a U.K.-based public relations firm representing Liberia. The U.S. company that makes it said the supply is now “exhausted.” Later Tuesday, Canada said it would provide some of its experimental Ebola vaccine for use in West Africa.