[1] Univ Florence, Dept Paediat, Italian Register HIV Infect Children, I-50132 Florence, Italy
[2] Univ Turin, Dept Paediat, I-10124 Turin, Italy
[3] Univ Florence, Dept Stat, I-50132 Florence, Italy
[4] Bambino Gesu Pediat Hosp, Rome, Italy
[5] Univ Milan, Inst Paediat, Fdn IRCCS, Osped Maggiore Policlin, I-20122 Milan, Italy
[6] Univ Milan, Paediat Clin, Sacco Hosp, I-20122 Milan, Italy
[7] Univ Padua, Dept Paediat, I-35100 Padua, Italy
[8] Univ Genoa, Infect Dis Unit, I-16126 Genoa, Italy
[9] S Martino Univ Hosp, Genoa, Italy
[10] Univ Naples Federico II, Dept Paediat, Naples, Italy