Keio University - Department of Pediatrics, Keio University - Department of Pediatrics, Keio University, National Hospital Organization Tochigi Medical Center - Department of Clinical Research, National Tokyo Medical Center - Department of Pediatrics, Keio University, Yokohama Municipal Citizen’s Hospital - Department of Pediatrics, Hiratsuka Hospital - Department of Pediatrics, Tokyo Metropolitan Ohtsuka Hospital - Department of Pediatrics, Tokyo Metropolitan Ohtsuka Hospital - Department of Pediatrics, Ota Memorial Hospital - Department of Pediatrics, Tokyo Dental College - Ichikawa General Hospital, Kawasaki Municipal Hospital - Department of Pediatrics, Japanese Red Cross Shizuoka Hospital, Shizuoka City Shimizu Hospital - Department of Pediatrics, Hino Municipal Hospital, Saitama Hospital - Department of Pediatrics, Saitama City Hospital, Sano Kosei General Hospital - Department of Pediatrics, Japanese Red Cross Ashikaga Hospital - Department of Pediatrics, Nippon Koukan Hospital - Department of Pediatrics, Keiyu Hospital, Eiju General Hospital - Department of Pediatrics and Keio University

affiliation not provided to SSRN, Japanese Red Cross Ashikaga Hospital - Department of Pediatrics, National Institute of Infectious Diseases, Keio University - Department of Pediatrics and Keio University