Performance of a Triage Protocol for Monoclonal Antibodies in a Mixed Vaccinated and Unvaccinated Cohort of COVID-19 Patients Treated With Intravenous Infusion or Subcutaneous Injection

Background Several monoclonal antibodies (mAbs) have been shown to reduce rates of hospitalization in patients with Covid-19 who have risk factors for severe disease. Due to capacity constraints, many health systems have been unable to provide mAbs to all eligible patients. There is little evidence regarding the performance of triage protocols for allocation or the relative effectiveness of subcutaneous administration versus intravenous infusion. Methods Retrospective cohort study of 1063 patients with Covid-19 consecutively referred for monoclonal antibody therapy in a single large academic health care system, who were prioritized for mAb therapy using an allocation protocol grouping patients by risk. Results A triage protocol prioritizing patients who were not fully vaccinated and at high risk of severe Covid-19 plus patients who were heavily immunosuppressed performed well in terms of differentiating between groups of patients by risk of severe disease. The number needed to treat (NNT) to prevent one hospitalization was 4.4 for the highest priority group, 8.5 for the next highest priority group, and 21.7 for the third highest priority group. There was no significant correlation between route of administration and hospitalization for symptoms related to Covid-19 (OR 1.26 in the IV group compared to the subcutaneous group, 95% CI [0.56-2.8], P =0.58). Conclusions This study demonstrates that triaging mAbs for patients with Covid-19 by risk can optimize benefit in terms of reducing rates of hospitalization and that rates of hospitalization may be no different between patients treated with subcutaneous injection and patients treated with intravenous infusion.