1. Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, China
2. Center for Primary Care and Outcomes Research, School of Medicine, Center for Health Policy, Freeman Spogli Institute for International Studies, Stanford University, Stanford, CA 94305-2004, USA
3. Vanke School of Public Health, Tsinghua University, Beijing 100084, China
4. Global Center for Infectious Disease and Policy Research & Global Health and Infectious Diseases Group, Peking University, Beijing 100191, China
5. Key Laboratory of Reproductive Health, National Health and Family Planning Commission of the People’s Republic of China, Beijing 100191, China