Sonia Shah is a science journalist and the author of PANDEMIC: Tracking Contagion from Cholera to Ebola and Beyond (Farrar, Straus & Giroux, 2016). Her fifth book, The Next Great Migration: The Beauty and Terror of Life on the Move, was published in June.
Research subjects in developing countries–often the poorest, the sickest and with the fewest options–become more vulnerable.