This study reports the results of an ongoing phase 2 trial (BLAZE-1) evaluating the efficacy and safety of the neutralizing antibody LY-CoV555 in patients with mild or moderate Covid-19. The trial involved 452 patients who received a single intravenous infusion of LY-CoV555 at three doses (700 mg, 2800 mg, or 7000 mg) or placebo. The primary outcome was the change in viral load at day 11, with a mean decrease of -3.81 in the log viral load for the entire population, indicating a reduction of over 99.97% of viral RNA. For patients receiving the 2800-mg dose, the decrease from baseline was -0.53 (95% CI, -0.98 to -0.08; P=0.02), corresponding to a lower viral load by a factor of 3.4 compared to placebo. Smaller differences were observed for the 700-mg and 7000-mg doses. Patients receiving LY-CoV555 had slightly lower symptom severity than those receiving placebo. The percentage of patients who had a Covid-19-related hospitalization or emergency department visit was 1.6% in the LY-CoV555 group and 6.3% in the placebo group. The study found that the 2800-mg dose of LY-CoV555 appeared to accelerate the natural decline in viral load over time, while the other doses did not by day 11. The safety profile of LY-CoV555 was similar to that of placebo, with no serious adverse events reported in the LY-CoV555 group and only 0.7% in the placebo group. The results suggest that LY-CoV555 may be a useful treatment for emergency use in patients with recently diagnosed Covid-19. The study was funded by Eli Lilly and was conducted in accordance with the Declaration of Helsinki and ethical guidelines. The findings indicate that LY-CoV555 could reduce the rate of hospitalization and symptom severity in patients with mild or moderate Covid-19.This study reports the results of an ongoing phase 2 trial (BLAZE-1) evaluating the efficacy and safety of the neutralizing antibody LY-CoV555 in patients with mild or moderate Covid-19. The trial involved 452 patients who received a single intravenous infusion of LY-CoV555 at three doses (700 mg, 2800 mg, or 7000 mg) or placebo. The primary outcome was the change in viral load at day 11, with a mean decrease of -3.81 in the log viral load for the entire population, indicating a reduction of over 99.97% of viral RNA. For patients receiving the 2800-mg dose, the decrease from baseline was -0.53 (95% CI, -0.98 to -0.08; P=0.02), corresponding to a lower viral load by a factor of 3.4 compared to placebo. Smaller differences were observed for the 700-mg and 7000-mg doses. Patients receiving LY-CoV555 had slightly lower symptom severity than those receiving placebo. The percentage of patients who had a Covid-19-related hospitalization or emergency department visit was 1.6% in the LY-CoV555 group and 6.3% in the placebo group. The study found that the 2800-mg dose of LY-CoV555 appeared to accelerate the natural decline in viral load over time, while the other doses did not by day 11. The safety profile of LY-CoV555 was similar to that of placebo, with no serious adverse events reported in the LY-CoV555 group and only 0.7% in the placebo group. The results suggest that LY-CoV555 may be a useful treatment for emergency use in patients with recently diagnosed Covid-19. The study was funded by Eli Lilly and was conducted in accordance with the Declaration of Helsinki and ethical guidelines. The findings indicate that LY-CoV555 could reduce the rate of hospitalization and symptom severity in patients with mild or moderate Covid-19.