1. Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong 999077, China.
2. Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong 999077, China.
3. Biostatistics and Clinical Research Methodology Unit, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong 999077, China.
4. Institute of Immunology, University of Science and Technology of China, Hefei, Anhui 230027, China.