BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes 
coronavirus disease 2019 (Covid-19), which is most frequently mild yet can be 
severe and life-threatening. Virus-neutralizing monoclonal antibodies are 
predicted to reduce viral load, ameliorate symptoms, and prevent 
hospitalization.
METHODS: In this ongoing phase 2 trial involving outpatients with recently 
diagnosed mild or moderate Covid-19, we randomly assigned 452 patients to 
receive a single intravenous infusion of neutralizing antibody LY-CoV555 in one 
of three doses (700 mg, 2800 mg, or 7000 mg) or placebo and evaluated the 
quantitative virologic end points and clinical outcomes. The primary outcome was 
the change from baseline in the viral load at day 11. The results of a 
preplanned interim analysis as of September 5, 2020, are reported here.
RESULTS: At the time of the interim analysis, the observed mean decrease from 
baseline in the log viral load for the entire population was -3.81, for an 
elimination of more than 99.97% of viral RNA. For patients who received the 
2800-mg dose of LY-CoV555, the difference from placebo in the decrease from 
baseline was -0.53 (95% confidence interval [CI], -0.98 to -0.08; P = 0.02), for 
a viral load that was lower by a factor of 3.4. Smaller differences from placebo 
in the change from baseline were observed among the patients who received the 
700-mg dose (-0.20; 95% CI, -0.66 to 0.25; P = 0.38) or the 7000-mg dose (0.09; 
95% CI, -0.37 to 0.55; P = 0.70). On days 2 to 6, the patients who received 
LY-CoV555 had a slightly lower severity of symptoms than those who received 
placebo. The percentage of patients who had a Covid-19-related hospitalization 
or visit to an emergency department was 1.6% in the LY-CoV555 group and 6.3% in 
the placebo group.
CONCLUSIONS: In this interim analysis of a phase 2 trial, one of three doses of 
neutralizing antibody LY-CoV555 appeared to accelerate the natural decline in 
viral load over time, whereas the other doses had not by day 11. (Funded by Eli 
Lilly; BLAZE-1 ClinicalTrials.gov number, NCT04427501.).