1. Health Economics Department, Institute for Preventive Medicine and Public Health, Hanoi Medical University, Hanoi, Vietnam.
2. Center for Health System Research, Hanoi Medical University, Hanoi, Vietnam.
3. Swiss Federal Institute of Aquatic Science and Technology (Eawag)
4. Swiss Tropical and Public Health Institute/University of Basel, Basel, Switzerland.
5. Department of Environmental Health, Hanoi School of Public Health, Hanoi, Vietnam.