Department of Respiratory and Critical Care Medicine, West China School of Medicine and West China Hospital, Sichuan University, Chengdu, China. Center for International Child Health, The University of Melbourne Department of Pediatrics, Murdoch Children's Research Institute and Intensive Care Unit, Royal Children's Hospital, Melbourne, Victoria, Australia. Center for International Child Health, The University of Melbourne Department of Pediatrics, Murdoch Children's Research Institute and Intensive Care Unit, Royal Children's Hospital, Melbourne, Victoria, Australia; Intensive Care Unit, Dhaka Hospital, Nutrition and Clinical Services Division, International Center for Diarrheal Disease Research, Bangladesh, Dhaka, Bangladesh. John Hunter Children's Hospital, Hunter Medical Research Institute, University of Newcastle GrowUpWell, Priority Research Center, Australia. Pediatric ICU, Rush University Children's Hospital, Chicago, IL. Division of Respiratory Care, Department of Cardiopulmonary Sciences, Rush University Medical Center, Rush University, Chicago, IL. Electronic address: Jie_Li@rush.edu.