1 Department of Clinical and Experimental Medicine, Section of Pediatrics, University of Pisa, Pisa, Italy.
2 Allergy, Immunology and Rheumatology Division, Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore City, Singapore.
3 Department of Clinical Immunology and Allergology, I.M. Sechenov First Moscow State Medical University, Moscow, Russia.