Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread 
rapidly worldwide. This study is the first to report the tolerability, safety, 
pharmacokinetics (PK), and immunogenicity of a recombinant human anti-SARS-CoV-2 
monoclonal antibody, etesevimab (CB6, JS016, LY3832479, or LY-CoV016), in 
healthy adults. This paper describes a randomized, double-blind, 
placebo-controlled, phase 1 study. A total of 40 participants were enrolled to 
receive a single intravenous dose of either etesevimab or placebo in one of four 
sequential ascending intravenous dose cohorts. All 40 participants completed the 
study. Seventeen (42.5%) participants experienced 22 treatment emergent adverse 
events (TEAEs) that were drug-related, and the rates of these TEAEs among 
different dose cohorts were numerically comparable. No difference was observed 
between the combined etesevimab group and the placebo group. The exposure after 
etesevimab infusion increased in an approximately proportional manner as the 
dose increased from 2.5 to 50 mg/kg. The elimination half-life (t1/2) value did 
not differ among different dose cohorts and was estimated to be around 4 weeks. 
Etesevimab was well tolerated after administration of a single dose at a range 
of 2.5 mg/kg to 50 mg/kg in healthy Chinese adults. The PK profiles of 
etesevimab in healthy volunteers showed typical monoclonal antibody distribution 
and elimination characteristics. (This study has been registered at 
ClinicalTrials.gov under identifier NCT04441918.).