1 Department of Respiratory Medicine, National Clinical Research Center of Respiratory Diseases, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, 56 Nan Li Shi Road, Xicheng District, Beijing, 100045, China.
2 Department of Respiratory Medicine, National Clinical Research Center of Respiratory Diseases, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, 56 Nan Li Shi Road, Xicheng District, Beijing, 100045, China. liuxiu_yun@126.com.
3 Department of Respiratory Medicine, National Clinical Research Center of Respiratory Diseases, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, 56 Nan Li Shi Road, Xicheng District, Beijing, 100045, China. xubaopingbch@163.com.