1. Division of Infectious Disease Control, Gyeonggi Provincial Government, Suwon, Korea.
2. WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
3. Institute for Occupational and Environmental Health, Korea University, Seoul, Korea.
4. Division of Infectious Disease Control, City Public Health Center, Yeoju, Korea.
5. Division of Infectious Diseases, Korea University College of Medicine, Seoul, Korea.