Correction: Assessment of Transmission in Trachoma Programs over Time Suggests No Short-Term Loss of Immunity. - Fengchen Liu; Travis C. Porco; Kathryn J. Ray; Robin L. Bailey; Harran Mkocha; Beatriz Muñoz; Thomas C. Quinn; Thomas M. Lietman; Sheila K. West (Public Library of Science (PLoS), 2013)