* I=Intermittent: FEV1 > 80 %, MEF > 65 %, symptom-free interval > 2 months; II= Mild Persistent: FEV1 > 80 %, MEF > 65 %, symptom-free interval < 2 months; III= Moderate persistent: FEV1 < 80 %, MEF < 65 %, symptoms several days a week; IV= Severe persistent: FEV1 < 60 %, Symptoms during the day and night. ** v, virus-induced; a, allergen-induced; e, exercise-induced; u, unresolved. ***al, Alternaria species; am, ambrosia; b, birch; ca, cat; f, Dermatophagoides mix; g, grass pollen mix; n.d., not done. **** FEV1% / PEF% predicted: Lung function results Pre-bronchodilation. CRP: C-reactive-protein; FEV1: forced expiratory volume in 1 second / forced vital capacity; PEF: peak expiratory flow; RV: Rhinovirus