1. Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, 27100 Pavia, Italy
2. Pediatric Clinic, Fondazione IRCCS Policlinico San Matteo, 27100 Pavia, Italy
3. Microbiology and Virology Department, Fondazione IRCCS Policlinico San Matteo, 27100 Pavia, Italy
4. Laboratory of Immuno-Allergology of Clinical Chemistry, Fondazione IRCCS Policlinico San Matteo, 27100 Pavia, Italy