1. Infectious Disease Surveillance Center, National Institute of Infectious Diseases , Tokyo , Japan
2. Department of Public Health and Welfare, Osaka City Public Health Office , Osaka , Japan
3. Division of Infection Control and Prevention, Osaka University Hospital , Osaka , Japan
4. Director, Toyama Institute of Health , Imizu , Japan
5. Department of Neonatology, Osaka Women’s and Children’s Hospital , Osaka , Japan
6. Department of Virology III, National Institute of Infectious Diseases , Tokyo , Japan