1. Center for Vaccine Evaluation and Study, Medical Research Institute, Ewha Womans University School of Medicine, Seoul, Korea.
2. Department of Pediatrics, Graduate School of Medicine, Gachon University, Incheon, Korea.
3. Departments of Pathology and Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA.
4. Department of Pediatrics, Ewha Womans University School of Medicine, Seoul, Korea.