Sue Desmond-Hellmann is using precision public health -- an approach that incorporates big data, consumer monitoring, gene sequencing and other innovative tools -- to solve the world's most difficult medical problems. It's already helped cut HIV transmission from mothers to babies by nearly half in sub-Saharan Africa, and now it's being used to address alarming infant mortality rates all over the world. The goal: to save lives by bringing the right interventions to the right populations at the right time.