1. State Key Laboratory of Respiratory Disease, Guangzhou Medical University, Guangzhou, People’s Republic of China
2. School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong SAR, People’s Republic of China
3. Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
4. Institute of Environmental Science and Research, Ltd., NCBID–Wallaceville, Wallaceville, New Zealand
5. Immunisation Advisory Centre (IMAC), University Services, University of Auckland, Auckland, New Zealand
6. Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, USA