[1] Univ Childrens Hosp, Paediat Emergency Med Serv, Geneva, Switzerland
[2] Univ Genoa, Genoa, Italy
[3] IRCCS AOU San Martino IST, Genoa, Italy
[4] Pediat Clin, Lisbon, Portugal
[5] Univ Florence, Florence, Italy
[6] Anna Meyer Childrens Hosp, Florence, Italy
[7] Dr Horst Schmidt Kliniken, Klinikum Landeshauptstadt Wiesbaden HSK, Wiesbaden, Germany
[8] Univ Med Mainz, Mainz, Germany
[9] Hosp Clin Univ Santiago de Compostela, Santiago, Spain
[10] Inst Invest Sanitaria Santiago, Genet Vaccines Infect & Pediat Res Grp GENVIP, Santiago, Spain
[11] Catholic Univ Louvain, Ctr Hosp Univ Mont Godinne, Dept Pediat, Yvoir, Belgium
[12] Pfizer Inc, Paris, France
[13] Univ Thessaly, Dept Pediat, Sch Hlth Sci, Fac Med,Gen Univ Hosp Larissa,Biopolis, Larisa, Greece