Neutralizing Monoclonal Antibody Treatment Reduces Hospitalization for Mild and Moderate COVID-19: A Real-World Experience.

BACKGROUND: Neutralizing monoclonal antibody (NmAb) treatments have received emergency use authorization to treat patients with mild or moderate COVID-19 infection. To date, no real- world data about the efficacy of NmAb has been reported from clinical practice. We assessed the impact of NmAb treatment given in the outpatient clinical practice setting on hospital utilization. METHODS: Electronic medical records were used to identify adult COVID-19 patients who received NmAbs [bamlanivimab (BAM) or casirivimab and imdevimab (REGN-COV2)] and historic COVID-19 controls. Post-index hospitalization rates were compared. RESULTS: 707 confirmed COVID-19 patients received NmAb and 1709 historic COVID-19 controls were included; 553 (78%) received BAM, 154 (22%) received REGN-COV2. Patients receiving NmAb infusion had significantly lower hospitalization rate (5.8% vs. 11.4%, p<0.0001); a shorter length of stay if hospitalized (mean 5.2 days vs. 7.4 days, p=0.02), and fewer ED visits within 30 days post-index (8.1% vs 12.3%, p=0.003) than controls. Hospitalization-free survival was significantly longer in NmAb patients compared to controls (p<0.0001). There was a trend towards a lower hospitalization rate among patients who received NmAb within 2-4 days after symptom onset. In multivariate analysis, having received a NmAb transfusion was independently associated with a lower risk of hospitalization after adjustment for age, sex, race, BMI and referral source: adjusted hazard ratio (95% CI) = 0.54 (0.38 - 0.79), p=0.0012. Overall mortality was not different between the two groups. CONCLUSIONS AND RELEVANCE: NmAb treatment reduced hospital utilization especially when received within a few days of symptom onset. Further study is needed to validate these findings.