[1] Univ Med Ctr Ulm, Dept Pediat & Adolescent Med, Ulm, Germany
[2] Univ Hosp, Dept Pediat, LMU Munich, Dr von Hauner Childrens Hosp, Munich, Germany
[3] Darmstadter Kinderklin Prinzessin Margaret, Dieburger Str 31, Darmstadt, Germany
[4] Univ Med Ctr Essen, Dept Pediat & Adolescent Med, Essen, Germany
[5] Univ Med Ctr Freiburg, Dept Pediat & Adolescent Med, Freiburg, Germany
[6] Univ Med Ctr Hamburg Eppendorf, Ctr Obstet & Pediat, Dept Pediat, Hamburg, Germany
[7] Univ Hosp Regensburg, Univ Childrens Hosp, Regensburg, Germany
[8] Klinikum Westbrandenburg, Dept Pediat & Adolescent Med, Potsdam, Germany
[9] Ulm Univ, Inst Epidemiol & Med Biometry, Ulm, Germany
[10] Univ Warmia & Mazury, Dept Pediat Gastroenterol & Nutr, Sch Med, Coll Med, Olsztyn, Poland
[11] Univ Med Ctr Ulm, Inst Virol, Ulm, Germany