1 Respiratory Diseases, University Modena R 2 Statistics, University Modena R 3 Pediatrics, University Modena R 4 Rheumatology, University Modena R 5 Dermatology, University Modena R 6 Infectious Diseases, University Modena R 7 Hematology, University Modena &Reggio Emilia, Modena, Italy and 8 Microbiology &Virology Laboratory, Policlinico Hospital, Modena, Italy.