Randomized trial of the safety and efficacy of anti-SARS-CoV-2 mAb in the treatment of patients with nosocomial COVID-19 (CATCO-NOS).

Background: Patients with nosocomial acquisition of COVID-19 have poor outcomes but have not been included in therapeutic trials to date.

Methods: A pragmatic open-label randomized controlled trial of anti-SARS-CoV-2 monoclonal antibodies (mAb) was performed in hospitalized patients with nosocomial COVID-19 infection in acute care hospitals spanning a provincial health care network. Participants within 5 days of first positive test or symptom onset were randomized to standard of care (SOC) plus a single dose intravenous mAb treatment (bamlanivimab or casirivimab/imdevimab) or SOC alone on a 2:1 basis. The primary study endpoint was the need for invasive mechanical ventilation (IMV) or inpatient mortality by day 60 after randomization.

Results: Forty-six participants were enrolled from 13 hospitals between February 14 and October 8, 2021: 31 in the mAb and 15 in the SOC arm. IMV or inpatient mortality up to day 60 occurred in 4 (12.9%) participants in the mAb versus 3 in the SOC arm (20.0%), difference of -7.1% (95% CI -22.5 to 13.4, = 0.67). The study was terminated early due to lack of equipoise as effectiveness of anti-viral therapies and mAb was published in similar high-risk patient populations.

Conclusions: The trial was underpowered to detect meaningful differences given its early termination. The study does highlight the feasibility of undertaking trials in this patient population using a pragmatic approach allowing for trial participation and treatment access across a large health care network and may serve as a template for future designs.