1. School of Public Health, Peking University, Beijing, China
2. China Center for Health Development Studies, Peking University, Beijing, China
3. Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
4. Peking University Health Science Center-Chinese Center for Disease Control and Prevention Joint Center for Vaccine Economics, Peking University, Beijing, China
5. Institute for Global Health and Development, Peking University, Beijing, China