1. Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA
2. Berman Institute of Bioethics, 1809 Ashland Avenue, Baltimore, MD 21205, USA
3. SAMRC/WITS Centre for Health Economics and Decision Science (PRICELESS SA), Office 233, 2nd floor, Wits Education Campus, 27 St Andrews Road, Parktown, Johannesburg 2193, South Africa
4. Center for Global Development, 2055 L St., Washington, DC 20036, USA