1. Health Services Research Unit, Singapore General Hospital, Singapore 169608, Singapore
2. MOH Holdings Pte Ltd., 1 Maritime Square, Singapore 099253, Singapore
3. Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
4. School of Medicine, Dentistry and Nursing, University of Glasgow, Glasgow G12 8QQ, UK
5. Department of Pharmacy, Singapore General Hospital, Singapore 169608, Singapore
6. Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
7. Department of Infectious Diseases, Singapore General Hospital, Singapore 169608, Singapore