[1] Hanoi Med Univ, Allergy, Hanoi, Vietnam
[2] Bachmai Hosp, Allergy & Clin Immunol, Hanoi, Vietnam
[3] Karolinska Inst, Unit Lung & Allergy Res, IMM, SE-17717 Stockholm, Sweden
[4] Gothenburg Univ, Dept Internal Med, Krefting Res Ctr, Gothenburg, Sweden
[5] Norrbotten Cty Council, OLIN Studies, Lulea, Sweden
[6] Univ Umea, Publ Hlth & Clin Med, Umea, Sweden