1. Institute of Pediatrics, University of Milan, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milan, Italy
2. Department of Virology, University Medical Center, Rotterdam, The Netherlands
3. Pediatric Emergency Unit, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milan, Italy