aAllergy Unit, Meyer Children's Hospital IRCCS, Florence

bDepartment of Health Sciences, University of Florence, Florence, Italy

cDivision of Allergy and Immunology, Boston Children's Hospital, Harvard Medical School, Boston, USA

Correspondence to Mattia Giovannini, MD, Allergy Unit, Meyer Children's Hospital IRCCS, Department of Health Sciences, University of Florence, Viale Pieraccini 24, 50139 Florence, Italy. Tel: +39 0555662472; e-mail: [email protected]