In an unusual twist of expedited drug access, Mapp Biopharmaceutical Inc., which has nine employees, released its experimental ZMapp drug, until now only tested on infected animals, for the two health workers. Kentucky BioProcessing LLC, a subsidiary of tobacco giant Reynolds American Inc. (RAI), manufactures the treatment for Mapp from tobacco plants.

The first patient, Kent Brantly, a doctor, was flown from Liberia to Atlanta on Aug. 2, and is receiving treatment at Emory University Hospital. Nancy Writebol, an aid worker, is scheduled to arrive in Atlanta today and will be treated at the same hospital, according to the charity group she works with. Both are improving, according to relatives and supporters.