Experimental no more - One of the main weapons that health care workers used to battle the horrific West African Ebola Epidemic has been approved by the US Food and Drug Administration (FDA).

This makes Merck's Ervebo the first FDA-approved Ebola vaccine, coming a month after the European Commission also gave it the nod.

New Jersey-based Merck first deployed and tested the vaccine during the Ebola epidemic that lasted from 2014 to 2016, finding it to be 100 percent effective when administered to patients at least ten days in advance of potential exposure.  It's not clear how long protection from the shot lasts, because the effectiveness of some inoculations can fade over time.  But for now, it is a major step in battling a virus whose very name strikes terror the world over.

"The FDA's approval of Ervebo is a major advance in helping to protect against the Zaire Ebola virus as well as advancing US government preparedness efforts," said Peter Marks, director of the FDA's Center for Biologics Evaluation and Research.

Merck is now ramping up production of Ervebo to make it widely available in the third quarter of 2020.  It has not established a price for the drug, but Merck is working with the global non-profit Gavi, the Vaccine alliance - whose work is to support promulgate vaccination programs, especially in sub-Saharan Africa.

"Merck has committed to making the vaccine available to Gavi-eligible countries at the lowest possible access price," a spokesperson said.