While Ebola virus disease in the U.S. is a rare occurrence, the FDA approval of Merck & Co. Inc.’s Ervebo, the agency’s first for preventing Ebola Zaire virus in people age 18 and older, will have a ripple effect across the world, especially Africa where its effects have been devastating for decades. Stockpiling such a vaccine is crucial to world safety as Ebola has long been a potential bioterrorism threat, especially after 9/11. In the world of theoretical biological warfare, where the virus could be weaponized and disseminated by aerosol, Ebola virus is considered the most dangerous, with fatality rates estimated between 25% to 90%.