1. School of Public Health, Fudan University, Key Laboratory of Public Health Safety, Ministry of Education, Shanghai
2. World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China
3. Department of Biostatistics, College of Public Health and Health Professions & College of Medicine, University of Florida, Gainesville
4. Center for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
5. Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia