Affiliation: | (1) Clinical Epidemiology, Communicable Disease Centre, Tan Tock Seng Hospital, Jalan Tan Tock Seng, Singapore;(2) Surveillance Branch, Communicable Diseases Division, Ministry of Health, College Road, Singapore;(3) Department of Internal Medicine, Singapore General Hospital, Outram Road, Singapore;(4) Department of Infectious Diseases, Communicable Disease Centre, Tan Tock Seng Hospital, Jalan Tan Tock Seng, Singapore |