Fudan University - Key Laboratory of Public Health Safety (Ministry of Education), Fudan University - Key Laboratory of Public Health Safety (Ministry of Education), Chinese Center for Disease Control and Prevention (China CDC) - National Immunization Program, Fudan University - Department of Social Medicine, Fudan University - Department of Epidemiology, Duke University - Duke Global Health Institute, Bill and Melinda Gates Foundation, Duke University - Duke Global Health Institute, Fudan University - Department of Epidemiology, Fudan University - Department of Epidemiology, Fudan University - Shanghai Institute of Infectious Disease and Biosecurity and Fudan University - Shanghai Institute of Infectious Disease and Biosecurity