1. Department of Social Medicine, National Center for Child Health and Development , Tokyo, Japan
2. Department of Epidemiology, Fielding School of Public Health, University of California Los Angeles, Los Angeles, CA, USA
3. Department of Pediatrics, UCLA Mattel Children's Hospital, University of California Los Angeles, Los Angeles, CA, USA
4. Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences , Okayama, Japan
5. Division of Infectious Diseases, Department of Medical Subspecialties, National Center for Child Health and Development , Tokyo, Japan
6. Department of Infectious Diseases, National Center for Global Health and Medicine , Tokyo, Japan
7. Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center, Knoxville, Tennessee , USA
8. Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu , Japan