1. Department of Epidemiology and Biostatistics, University of California, San Francisco (UCSF) School of Medicine, 550 16th St, San Francisco, CA 94158, USA
2. UCSF Institute for Global Health Sciences, 550 16th St, San Francisco, CA 94158, USA
3. Sidney Kimmel Medical College, 1025 Walnut St, Philadelphia, PA 19107, USA
4. The William and Flora Hewlett Foundation, 2121 Sand Hill Road, Menlo Park, CA 94025, USA
5. Kenya Medical Research Institute, Mbagathi Rd, Nairobi, Kenya
6. New York University Rory Meyers College of Nursing, 433 First Avenue, New York, NY 10010, USA