1. Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Korea.
2. Department of Pediatrics, Seoul National University College of Medicine, Seoul, Korea.
3. Department of Pediatrics, Chung-Ang University Hospital, Seoul, Korea.
4. Department of Pediatrics, Jeonbuk National University Medical School, Jeonju, Korea.
5. Department of Pediatrics, Eunpyeong St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
6. Division of Pulmonary, Critical Care and Sleep Medicine, Eunpyeong St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
7. Department of Surgery, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea.
8. Department of Pediatrics, National Health Insurance Corporation Ilsan Hospital, Goyang, Korea.
9. Department of Pediatrics, Korea University Anam Hospital, Seoul, Korea.
10. Division of Infectious Diseases, Department of Internal Medicine, Incheon Medical Center, Incheon, Korea.
11. Korea Disease Control and Prevention Agency, Cheongju, Korea.