1. Faculty of Medicine; Associate Professor of Pediatrics and Pediatric Hematology/Oncology; Democritus University of Thrace; Alexandroupolis Greece
2. Department of Pediatrics; Hippokration General Hospital; Thessaloniki Greece
3. Werner and Gertrude Henle Professor of Pediatrics; Professor of Epidemiology; Perelman School of Medicine at the University of Pennsylvania; Chief, Division of Infectious Diseases; The Children's Hospital of Philadelphia; Philadelphia PA USA