1. Department for Health Systems Policies and Workforce, World Health Organization, avenue Appia 20, 1211 Geneva 27, Switzerland.
2. School of Public Health and the Goldman School of Public Policy, University of California, Berkeley, United States of America.
3. Health Systems and Services, World Health Organization Regional Office for Africa, Brazzaville, Congo.
4. Department for Health Statistics and Informatics, World Health Organization, Geneva, Switzerland.