1. Prince of Wales Hospital, Accident and Emergency Department, 30–32 Ngan Shing Street, Shatin, N.T., Hong Kong
2. Prince of Wales Hospital, Department of Microbiology, 30–32 Ngan Shing Street, Shatin, N.T., Hong Kong
3. The Chinese University of Hong Kong, Centre for Clinical Trials and Epidemiological Research, Faculty of Medicine, Shatin, N.T., Hong Kong
4. The Chinese University of Hong Kong, Accident & Emergency Medicine Academic Unit, Shatin, N.T., Hong Kong