Study design and participants
There are two stages in the DEFLECT. Stage 1 is designated to determine the optimal dose and primary endpoints for stage 2. The trial was registered at ClinicalTrials.gov (NCT04586153).This randomized controlled trial was carried out at nine sites in United States, Brazil, Pakistan, and Mexico in accordance with the ethical principles of the Declaration of Helsinki, the Good Clinical Practice guidelines, and all applicable regulatory requirements. The trial conduct and documentation were overseen by the local institutional review board or ethics committee at each trial centre. Additional details regarding the trial design are provided in the protocol (Supplementary Note The analysis described here involved 201 patients enroled in the trial to examine the safety and efficacy of meplazumab. All enroled patients were adults (≥18 years of age) with severe COVID-19 (grade 3 or 4 on a six-point ordinal scale, a modified ordinal scale recommended by the World Health Organization R&D Blueprint Group) and without COVID-19 vaccination within 2 weeks prior to randomization. The details of six-point ordinal scale were described in Supplementary Note 