1. Seoul Center for Infectious Disease Control, Seoul, Korea.
2. Department of Epidemiology, Graduate School of Public Health, Seoul National University, Seoul, Korea.
3. Division of VPD Control and NIP, Korea Centers for Disease Control and Prevention, Cheongju, Korea.
4. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
5. Department of Family Medicine, Seoul National University College of Medicine, Seoul, Korea.
6. JW Lee Center for Global Medicine, Seoul National University College of Medicine, Seoul, Korea.