1. Pudong Institute for Health Development; Shanghai 200129 China
2. School of Public Health; Fudan University; Shanghai 200031 China
3. Pudong New Area Health and Family Planning Commission; Shanghai 200125 China
4. Global Health, Community Engagement; University of Alberta; Edmonton Alberta T6G 1C9 Canada
5. Pudong New Area New Rural Cooperative Medical Scheme Management Office; Shanghai 201300 China