1 Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore. Andrew_yunkai_li@nuhs.edu.sg.
2 Division of Respiratory and Critical Care Medicine, Department of Medicine, National University Hospital, Singapore, Singapore. Andrew_yunkai_li@nuhs.edu.sg.
3 Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
4 Division of Respiratory and Critical Care Medicine, Department of Medicine, National University Hospital, Singapore, Singapore.
5 Medical Affairs, Alexandra Hospital, Singapore, Singapore.