Background <p>Reducing inappropriate use of antibiotics is essential to combat antimicrobial resistance. Antibiotics are widely prescribed upon hospital admission for acute respiratory infections, but it remains unknown whether it is safe to discontinue antibiotics when a respiratory virus is detected in these patients. With this randomized trial, we aim to assess the efficacy and safety of discontinuing antibiotic therapy in patients admitted to the hospital with a polymerase chain reaction test positive for respiratory virus and no clear evidence of bacterial infection.</p> Methods <p>ATHENIAN is an ongoing multicenter, open-label, pragmatic, randomized non-inferiority trial. We aim to recruit 400 adult patients initiated on antibiotic therapy at admittance to one of the 10 study sites in Norway and with a positive polymerase chain reaction test for influenza virus, human metapneumovirus, respiratory syncytial virus, or parainfluenza virus. The participants are randomized to intervention, discontinuation of antibiotic therapy, or control, continuation of antibiotic therapy at the discretion of the treating physician. We hypothesize that discontinuation of antibiotic therapy is safe and non-inferior to continuation of antibiotic therapy. The primary outcome, assessed at 120&#xa0;h after randomization, is early clinical response, defined as survival with symptom improvement without receipt of rescue antibacterial therapy. Secondary outcomes include all-cause in-hospital and 30-day mortality, duration of hospital admission, days of therapy with antibiotics, rescue antibiotic therapy during hospital admission, new antibiotic therapy for presumed airway infection up to 30&#xa0;days after hospital discharge, and hospital readmissions within 30 days after hospital discharge.</p> Discussion <p>To our knowledge, ATHENIAN is the first randomized controlled trial assessing the safety and efficacy of antimicrobial de-escalation based on multiplex nucleic acid amplification test results. Addressing this knowledge gap using a pragmatic study design will provide valuable insights that may influence treatment algorithms and antibiotic prescription practices. The study has the potential to contribute to a reduction in the inappropriate use of antibiotics and the emergence of antimicrobial resistance.</p> Trial registration <p>ClinicalTrials.gov NCT05045612. Registered on September 7, 2021.</p>