1Division of Infectious Diseases, Department of Medical Subspecialties, National Center for Child Health and Development, Tokyo, Japan
2Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan
3Department of Social Medicine, Research Institute, National Center for Child Health and Development, Tokyo, Japan
4Division of Infectious Diseases, Department of Pediatrics, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan
5Division of Infectious Diseases, Department of Pediatrics, Hyogo Prefectural Kobe Children Hospital, Kobe, Japan
6Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, USA