Does Vitamin D Supplementation Enhance Resolution of Inflammation After Community-acquired Pneumonia?

Inclusion Criteria: 1. Adults ≥50 years of age 2. Vitamin D deficiency at entry, defined as a serum total 25(OH)D concentration \<50 nmol/L 3. Admission to hospital with an acute illness (≤21 days) consistent with community-acquired pneumonia - at least one symptom of a lower respiratory tract infection (cough, sputum production, dyspnoea, wheeze, chest discomfort or pain, fever) and new infiltrate on chest radiograph 4. Adequate mental capacity to give informed consent for participation in the study and gives written informed consent Exclusion Criteria: 1. Currently taking any vitamin D supplementation 2. Known HIV infection, other condition causing immunosuppression, current immunosuppressive therapy or systemic corticosteroids 3. Known malignancy not in remission for \>3 years or terminal illness with prognosis \<1year 4. History of smoking within the previous 1 year 5. Known or suspected diagnosis of chronic obstructive pulmonary disease (COPD) 6. Previous hospitalisation within 10 days of admission 7. Aspiration pneumonia diagnosed by the clinical team 8. Known diagnosis of cystic fibrosis, bronchiectasis or interstitial lung disease at screening 9. Complications of pneumonia such as empyema or lung abscess at entry 10. Recent acute coronary syndrome within the previous 1 month 11. Long term oxygen therapy, chronic mechanical ventilation dependency or other contraindication to sputum induction 12. Serum corrected calcium concentration \>2.65 mmol/L at entry 13. Chronic kidney disease stage 4-5 (estimated glomerular filtration rate \<30ml/min) on an existing blood sample from the current hospital admission 14. Known clinical diagnosis of liver failure 15. Known or suspected diagnosis of active pulmonary tuberculosis 16. Known diagnosis of primary hyperparathyroidism 17. Known diagnosis of sarcoidosis 18. Known diagnosis of nephrolithiasis 19. Taking carbamazepine, phenytoin, phenobarbital, primidone, cardiac glycosides or benzothiadiazines with concomitant calcium supplementation at entry 20. Known allergy to vitamin D or its excipients 21. Currently taking part in another research study