1 Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore; Department of Respiratory and Critical Care Medicine, Tan Tock Seng Hospital, Singapore. Electronic address: schotirmall@ntu.edu.sg.
2 Child and Maternal Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia; Department of Respiratory and Sleep Medicine, Queensland Children's Hospital, Children Centre for Health Research, Queensland University of Technology, Brisbane, QLD, Australia.
3 Division of Molecular and Clinical Medicine, University of Dundee, Dundee, England.