Chest CT-scan for the Diagnosis of Community-acquired Pneumonia

Inclusion Criteria: * Patient above 18 years of age * Patient with a presumptive diagnosis of CAP according to attending ED physician * Patient experiencing at least one systemic sign (T°\>38°C or \< 36°C, HR\>90/min, RR\>20/min) * Patient experiencing one respiratory sign (cough, lateral chest pain, localized crackles, dyspnea) that recently appeared * Patient with a prior medical examination, the results have been or will be communicated * Patient gave written informed consent or in cases of emergency parent/ support person who gave written informed consent if he/she is present on the day of inclusion Exclusion Criteria: * Pregnancy * Patient with shock * Patient with respiratory distress and immune suppression * Patient with other criteria for immediate ICU referral to ICU * Patient with living conditions making it impossible to follow 28 days * Patient not affiliated with a social security system