1. Director for Epidemiological Investigation Analysis, Korea Disease Control and Prevention Agency, Cheongju, Korea.
2. Department of Preventive Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
3. Korea Insurance Development Institute, Seoul, Korea.
4. Department of Pediatrics, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.
5. Division of Infectious Diseases, Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, Seoul, Korea.