Lastly, we saw downstream evidence of IL-4 and IL-13 signaling blockade in the dupilumab group through analysis of immune biomarkers over time.<h4>Interpretation</h4>Dupilumab was well tolerated and improved 60-day survival in patients hospitalized with moderate to severe COVID-19.<h4>Trial registration</h4>This trial is registered with ClinicalTrials.gov, NCT04920916 .<h4>Funding</h4>Virginia Biosciences Health Research Corporation, PBM C19, Henske Family Foundation, National Institutes of Health, National Cancer Institute. The gene discussed is IL4; the disease is COVID-19.