Effectiveness of subcutaneous monoclonal antibody treatment in emergency department outpatients with COVID-19

Area of Science:

• Infectious Diseases
• Immunology
• Clinical Medicine

Background:

• Coronavirus disease 2019 (COVID-19) poses a significant public health challenge, necessitating evaluation of effective treatments.
• Neutralizing monoclonal antibodies (mAbs) have emerged as a therapeutic option for COVID-19, particularly for high-risk individuals.
• The optimal setting and impact of mAb administration, such as in the emergency department (ED), require further investigation.

Purpose of the Study:

• To determine if subcutaneous monoclonal antibody (mAb) treatment in the emergency department (ED) setting reduces hospitalizations, mortality, and disease severity in COVID-19 patients.
• To compare outcomes between mAb-eligible COVID-19 patients receiving subcutaneous casirivimab and imdevimab versus untreated controls.
• To assess the association of early mAb treatment with key clinical endpoints, including 28- and 90-day hospitalization and mortality.

Main Methods:

• A retrospective observational cohort study was conducted using data from ED patients diagnosed with COVID-19.
• Propensity score-matched analysis compared patients who received subcutaneous casirivimab and imdevimab with a control group of untreated COVID-19 patients.
• Primary outcome was 28-day all-cause hospitalization; secondary outcomes included 90-day hospitalization, 28- and 90-day mortality, and ED length of stay (LOS).

Main Results:

• No significant difference in 28-day or 90-day hospitalization rates was observed between the treated and untreated groups.
• Subcutaneous mAb treatment was associated with substantially lower 28-day and 90-day mortality rates.
• Among hospitalized patients, those treated with mAbs experienced shorter hospital and intensive care unit (ICU) LOS and reduced severity of illness.

Conclusions:

• Emergency department subcutaneous casirivimab/imdevimab treatment for symptomatic COVID-19 during the Delta variant phase was not linked to reduced hospitalizations.
• However, this early mAb treatment demonstrated a significant association with decreased mortality at both 28 and 90 days post-treatment.
• The study indicates that ED-administered subcutaneous mAbs can reduce the severity of illness and length of hospital stay for COVID-19 patients.