GEneRating Mucosal Immunity After INfluenzA Infection and Vaccination in Lung and Lymphoid TissuE

Inclusion Criteria: * Adults aged between 18-55 years inclusive * Sero-suitable as defined by a serum micro-neutralisation titre \<1:20 * Female participant who is not of child-bearing potential as assessed by an investigator OR is willing and able to use contraception as described in the protocol * Male participants who are willing to use one of the contraception methods described in the protocol * In good health with no clinically significant medical conditions Exclusion Criteria * History of clinically significant/currently active conditions; * Cardiovascular, thromboembolic/cerebrovascular disease. * Types of chronic respiratory disease in adulthood. * Significant wheeze in the past * Respiratory symptoms including wheeze, resulting in hospitalisation * Known bronchial hyperactivity to viruses * Diabetes mellitus * Migraine with associated symptoms like hemiplegia/vision loss. Cluster headache/migraine/prophylactic treatment for migraine. * History of autoimmune disease/known immunodeficiency of any cause * Immunosuppression. * Known coagulation disorder/anticoagulant therapy * Psychiatric illness including participants with a history of depression and/or anxiety with associated psychiatric comorbidities * Other major disease that, under the PI's discretion, could interfere with the participant completing the study. * Concurrent serious illness including history of malignancy that could interfere with the study or a participant completing the s…