1 Department of Medicine and Therapeutics, Prince of Wales Hospital, Stanley Ho Centre for Emerging Infectious Diseases, The Chinese University of Hong Kong, Hong Kong.
2 Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong.
3 Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China.
4 Department of Medicine and Geriatrics, United Christian Hospital, Hong Kong.
5 Department of Pathology, United Christian Hospital, Hong Kong.
6 Department of Medicine and Therapeutics, Prince of Wales Hospital, Hong Kong.
7 Pubic Health Laboratory Services Branch, Department of Health, Centre for Health Protection, The Government of Hong Kong SAR, Hong Kong.
8 Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China. Electronic address: paulkschan@cuhk.edu.hk.