Influenza Vaccination and COPD Phenotypes

Inclusion Criteria: Patients aged 65-85 years with a diagnosis of COPD (according to Global Initiative for Chronic Obstructive Lung Disease criteria: post bronchodilator FEV1/FVC ratio \<0.70) and moderate to severe airflow limitation (FEV1 30-80% predicted) who opt to receive the annual influenza vaccine. We will also include healthy participants aged 65-85 years without symptoms of lung disease who opt to receive the annual influenza vaccine. Exclusion Criteria: * Unable/unwilling to provide informed consent * Any history of allergies, suspected hypersensitivity and/or contraindication to vaccines (e.g egg protein allergy) * Participation in another clinical trial (use of investigational product or device) * Not on optimal treatment (COPD patients only) * Current smokers, exhaled CO \>10 parts per million * Clinical instability, defined as experiencing a COPD exacerbation less than 4 weeks prior to baseline visit, as indicated by treatment with systemic glucocorticosteroids and/or antibiotics and/or hospitalization (COPD only) * An upper/lower respiratory tract infection e.g. common cold, sinus symptoms, pneumonia, which has not resolved four weeks prior to baseline visit * Diagnosis of asthma and/or other relevant lung disease (e.g. history of primary or clinically significant bronchiectases, cystic fibrosis, bronchiolitis, lung resection, lung cancer, interstitial lung disease \[e.g. fibrosis, silicosis, sarcoidosis\], active tuberculosis) * Known alpha-1-antitrypsin deficiency * Immunological diseases or known infection with Human Immunodeficiency Virus (HIV) * Any diagnosis of a malignant disease (other than basal or squamous cell carcinoma) in the last 5 years * Currently taking immunosuppressive medications * Diagnosis of diabetes mellitus * Severe renal failure (calculated eGFR less than 60 ml/min) * Liver impairment Child-Pugh B/C and/or active viral hepatitis * Severe psychiatric or neurological disorders (Parkinson's disease or motor neurone disease) * Planned donation of human tissue (blood, organs or bone marrow) during the course of the trial