treatment-emergent serious adverse event related to treatment, two (2%) patients reported an adverse event of special interest, and two (2%) reported a new-onset chronic disease. Interpretation In patients in the ICU receiving mechanical ventilation with qPCR-confirmed S aureus colonisation of the lower respiratory tract, the incidence of S aureus pneumonia at 30 days was not significantly lower following treatment with 5000 mg suvratoxumab than with placebo. Despite these negative results, monoclonal antibodies still represent one promising therapeutic option to reduce antibiotic consumption that require further exploration and studies. Funding AstraZeneca, with support from the Innovative Medicines Initiative Joint Undertaking. Copyright (c) 2021 Elsevier Ltd. All rights reserved.