1. Department of Prevention of Mother to Child Transmission of Disease, National Center for women and children’s health, China Center for Disease Control and Prevention, Beijing, People’s Republic of China
2. Centre for Health Behaviours Research, JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, People’s Republic of China
3. Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, People’s Republic of China
4. Department of Health Policy and Management, John Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
5. World Health Organization, Western Pacific Regional Office, Manila, Philippines