1 National Centre for Infectious Diseases, Singapore 308422, Singapore; Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.
2 Ministry of Health Singapore, Singapore.
3 National Centre for Infectious Diseases, Singapore 308422, Singapore; Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
4 National Centre for Infectious Diseases, Singapore 308422, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
5 National Centre for Infectious Diseases, Singapore 308422, Singapore; Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Electronic address: yee_sin_leo@ncid.sg.