1. Department of Clinical Infectious Diseases, Kawasaki Medical School, Kurashiki, Okayama, Japan
2. Pediatric Department, Niigata Prefectural Shibata Hospital, Shibata, Niigata, Japan
3. Pediatric Department, Nakano Children’s Clinic, Shibata, Niigata, Japan
4. Pediatric Department, Sudo Pediatric Clinic, Shibata, Niigata, Japan
5. Pediatric Department, Kuwajima Clinic, Shibata, Niigata, Japan
6. Pediatric Department, Twin Smile Clinic, Shibata, Niigata, Japan
7. Department of Virology, Niigata Prefectural Institute of Public Health and Environmental Sciences, Niigata, Japan