Two American aid workers infected with Ebola are getting an experimental drug so novel it has never been tested for safety in humans and was only identified as a potential treatment earlier this year, thanks to a longstanding research program by the U.S. government and the military. The workers, Nancy Writebol and Dr. Kent Brantly, are improving, although it's impossible to know whether the treatment is the reason or they are recovering on their own, as others who have survived Ebola have done. Brantly is being treated at a special isolation unit at Atlanta's Emory University Hospital, and Writebol left Liberia at 1:12 a.m. local time Tuesday in the same specially equipped plane that brought Brantly.