1. Australian Red Cross Blood Service-Endeavour, Sydney, NSW 2000, Australia
2. Department of Microbiology, The Chinese University of Hong Kong, Hong Kong
3. Research Unit of Transfusion Medicine and Immunogenetics, Faculty of Medicine, University of Sydney, Sydney, Australia
4. Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong
5. Stanley Ho Centre for Emerging Infectious Diseases, School of Public Health, The Chinese University of Hong Kong, Hong Kong