Aspirin in Acute Pneumonia in the Elderly: a Multicenter, Double-blind, Randomized, Placebo-controlled Trial.

Inclusion Criteria: * Informed consent obtained from patient or relative/trusted person if patient unable to consent * Age ≥75 years * Clinical diagnosis of AP, presumed to be of bacterial or viral origin, with at least two of the following signs or symptoms: * cough, * purulent expectoration, * thoracic pain, * dyspnea/tachypnea, * temperature \> 37.8°C or \< 36°C, * unilateral crackles * Patient hospitalized for at least 48 hours * Onset of clinical signs \< 7 days * New radiological infiltrate documented by X-ray, ultrasound or CT scan Exclusion Criteria: * Mechanically ventilated pneumonia * Documented SARS CoV2 pneumonia * Patient with at least 3 episodes of inhalation pneumonitis in the 12 months prior to inclusion * Pre-acute episode swallowing disorders impairing oral medication intake * Physician-assessed life expectancy \< 90 days * Anticoagulant treatment (curative doses) * Antiplatelet therapy * Steroidal or non-steroidal anti-inflammatory treatment or oral corticosteroids without proton pump inhibitor (PPI) * Treatment with methotrexate (\>20 mg per week), anagrelide, probenecid, nicorandil, defibrotide * Dyspepsia or gastroesophageal reflux disease (GERD) without PPI use * Contraindications to aspirin (preventive doses) or its placebo at the time of inclusion: * Hypersensitivity to acetylsalicylic acid or to any of the excipients of the investigational drug or placebo * History of asthma induced by the administration of salicylates or non-steroidal anti-inflammatory drugs * Active peptic ulcer disease or history of recurrent peptic ulcer disease * History of cerebrovascular haemorrhage * Previous gastrointestinal hemorrhage * History of hemorrhage with Hemoglobin \> 3g /dl requiring transfusion, vasoactive treatment or surgery * Known hereditary or acquired coagulation disorder * Thrombocytopenia (platelets \< 50 giga/L) * Acute kidney injury (clairance \< 15 ml/min selon MDRD - Modification of Diet in Renal Disease), * Liver cirrhosis or acute liver failure (PTT\<50%), * Severe uncontrolled heart failure * Persistente severe hypertension (PAS \> 180mmHg) * Patient with mastocytosis * Person not affiliated to a national social security scheme * Patient under court protection