Inclusion Criteria:  Patient who provides his/her written informed Consent to participate prior to commencing any study related activities. Children & Adolescent aged 6-17 years at mepolizumab initiation Patient with a current clinical diagnosis of severe asthma (as per GINA / ATS / ERS / BTS criteria) and eosinophilic phenotype (as per mepolizumab licence) at mepolizumab initiation Patient currently under treatment or who initiates treatment with mepolizumab at the inclusion visit based on national asthma guidelines. Patient with relevant paper or electronic-based medical records available for 12-months prior to enrolment date/ index date (date of first mepolizumab injection) for clinically significant asthma exacerbation.  Exclusion Criteria:  A participant will not be eligible for inclusion in this study if any of the following criteria apply: 3. Patient who does not meet the inclusion criteria. 4. Patient who has participated in an asthma monoclonal antibodies drug interventional clinical trial in the previous 12-months to mepolizumab initiation.