Ethical challenges of big data in public health.

Vayena E Institute of Biomedical Ethics, University of Zurich, Zurich, Switzerland.
Salathé M Center for Infectious Disease Dynamics, Department of Biology, Penn State University, University Park, Pennsylvania, United States of America.
Madoff LC ProMED (Program for Monitoring Emerging Diseases), International Society for Infectious Diseases and University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.
Brownstein JS Children's Hospital Informatics Program, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.