1 Department of Paediatrics, Khoo Teck Puat- National University Children's Medical Institute, National University Health System, Singapore.
2 Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
3 Department of Laboratory Medicine, National University Health System, Singapore.
4 Division of Infectious Diseases, National University Health System and Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.