Randomization and masking
The study is a third-party double-blind study for all investigational staff who make determinations related to the study. The baseline data was collected, including information on demographic characteristics, concomitant antiviral agents, SARS-CoV-2 vaccination status, and clinical severity. Patients meet the criteria were assigned to four groups (0.12 mg/kg, 0.2 mg/kg, 0.3 mg/kg, or placebo) using a randomization code at a ratio of 1:1:1:1. Randomization was stratified by severity and age (age < 65 years or ≥65 years). The randomization schedule was created by the designee and stored in a secure area, and the randomization list was transferred via E-mail by unblinded study team leader. All patients received the standard of care (SoC) in compliance with the local practice. On the day of infusion, meplazumab (diluted in 0.9% saline) or placebo (0.9% saline) was administered intravenously. The solutions were indistinguishable, prepared by an unblinded third party (e.g., a pharmacist or nurse), and administered by an authorized blinded site staff member.