Even as an unapproved investigational vaccine, Merck’s Ebola shot played a key role in fighting the ongoing outbreak in Congo. Now, though, the shot has its FDA approval, right on the heels of its first nod in Europe. After the European Commission signed off on the vaccine in November, the U.S. FDA just endorsed the shot, dubbed Ervebo. The FDA nod "represents another important milestone in the global response to Ebola Virus Disease and stands as a tremendous accomplishment by a unique global partnership,” Merck’s R&D head Roger Perlmutter said in a statement. To date, the company has supplied about 275,000 investigational doses to help fight the outbreak in Congo, which has claimed more than 2,200 lives. Meanwhile, officials in nearby Rwanda recently signed off on a program to deploy Johnson & Johnson’s investigational vaccine to people two and older in border regions. The company will supply about 200,000 doses for that effort. RELATED: Merck's Ervebo, the world's first Ebola shot, wins inaugural approval in EU The Congo Ebola outbreak is the second-deadliest in history, following the 2014 outbreak in West Africa that killed more than 11,000 people. Merck licensed the vaccine from NewLink Genetics amid that previous outbreak and accelerated development with numerous partners. Scientists at the Public Health Agency of Canada’s National Microbiology Laboratory originally developed the vaccine. Merck is now starting to manufacture licensed doses, which are expected to be available in the third quarter of 2020. The drugmaker will continue to work with authorities to provide investigational doses in the meantime.