<qa>  What is the treatment period for subjects with severe eosinophilic asthma?The study will be a multi-centre, open-label single arm trial. Patients with severe eosinophilic asthma who are receiving omalizumab, but are not optimally controlled will be eligible to participate. Subjects will remain on their current maintenance therapy including omalizumab throughout the run-in period for a minimum of one week and up to 4 weeks. At Visit 2 week 0 subjects will discontinue their omalizumab treatment and be switched to mepolizumab 100 mg subcutaneous SC every 4 weeks for 28 weeks. The treatment period is 32 weeks, including an Exit VisitEarly Withdrawal Visit, 4 weeks following the subjects last dose of mepolizumab. 