1. Department of Pediatrics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Office for Infection Control, Asan Medical Center, Seoul, Korea.
3. Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
4. Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.