1. Department of Behavioral and Social Sciences, School of Public Health, Brown University, Providence, Rhode Island.
2. Department of Behavioral Social Sciences, School of Medicine, College of Health Sciences, Moi University, Eldoret, Kenya.
3. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
4. Department of Epidemiology and Biostatistics, School of Public Health, College of Health Sciences, Moi University, Eldoret, Kenya.
5. Department of Health Services, Policy & Practice, School of Public Health, Brown University, Providence, Rhode Island.