Antibiotic Therapy in Viral Airway Infections

Inclusion Criteria: * Hospitalized * Adults 18 year or older * Moderately severe disease (CRB65 ≤ 2 at time of inclusion) * Nasopharyngeal swab positive for influenza virus, parainfluenza virus, respiratory syncytial virus (RSV) or human metapneumovirus (hMPV) * On antibiotic therapy as instituted by the receiving physician from the emergency department * Signed informed consent must be obtained and documented according to ICH GCP, and national/local regulations. Exclusion Criteria: * Requiring ICU admission at screening * Requiring high-flow oxygen therapy or non-invasive ventilation at screening * Signs of severe pneumonia (abscesses, massive pleural effusion, a well-defined lobar infiltrate on chest X-ray strongly suggestive of bacterial etiology) * Not immunocompetent (i.e. on active chemotherapy, corticosteroid therapy equaling ≥ 20 mg prednisolone daily for ≥ 4 weeks, chronic immunosuppression due to solid organ transplant) * SARS-CoV-2 positive * Bacteremia * Urine antigen test positive for legionella * Any other infection necessitating antibiotic treatment * Antibiotic use for assumed airway infection within the last 24 hours before admission to hospital * Time from initiation of antibiotic therapy to screening \>48 hours