Treatment with a combination of two monoclonal antibodies - casirivimab and imdevimab - reduces the risk of hospitalization in high-risk patients with mild to moderate Covid-19, reports a new study published August 30, 2021in EClinicalMedicine¹, a journal published by The Lancet.

Casirivimab and imdevimab are recombinant human IgG1 monoclonal antibodies that bind non-competitively to the spike protein receptor-binding domain of SARS-CoV-2 and prevent the virus from entering the cells. Last year in November, the combination of casirivimab–imdevimab was approved for emergency use by the US FDA for outpatient treatment of high-risk patients with mild to moderate COVID-19.

The multicenter retrospective study included 696 patients, who were treated with casirivimab–imdevimab between December 4, 2020 and April 9, 2021 at Mayo Clinic. The control group also included 696 patients who did not receive the monoclonal antibodies combination. Follow up was done at 14, 21 and 28 days after treatment to evaluate the rate of hospitalization.

The study group included patients who had co-existing conditions such as hypertension, body mass index (BMI) ≥35, diabetes, chronic lung disease, chronic renal disease, congestive heart failure. Most of them were aged 65 years or older. Almost half of the study population was female.

Results showed that 1.3% of patients treated with monoclonal antibodies needed hospitalization due to any cause on the 14th day compared to 3.3% in the control group. At Day 21, 1.3% treated patients were hospitalized versus 4.2% of patients who did not receive the study treatment. The number of patients hospitalized was again found to be lower in the treated group versus the untreated group; 1.6% versus 4.8%, respectively. ICU admission and mortality rates were low in patients who were hospitalized.

This study has shown that casirivimab–imdevimab combination significantly reduced the need for all-cause hospitalization within 28 days of treatment in high-risk patients with mild to moderate COVID-19. Though some patients needed admission to hospital, there were more hospital days saved and more patients could be managed at home signifying that the monoclonal antibodies also reduced the burden on hospitals and healthcare systems.

Reference

1. Razonable RR, et al. Casirivimab–Imdevimab treatment is associated with reduced rates of hospitalization among high-risk patients with mild to moderate coronavirus disease-19. EClinicalMedicine, 2021; 101102 DOI: 10.1016/j.eclinm.2021.101102.