Comparison of Monoclonal Antibody Cocktail (Casirivimab-Imdevimab) Treatment With Remdesivir and Favipiravir in Mild to Moderate COVID-19 Infection: A Retrospective Study

Introduction: Favipiravir and remdesivir are antiviral drugs being used in the COVID pandemic and were also used previously for other viral infections in the past. Monoclonal antibody (Mab) Casirivimab-Imdevimab is a Coronavirus Disease 2019 neutralising antibody approved in the last one year. Therefore, a clinical comparison with the existing treatment modalities is imperative.

Aim: To compare Mab with remdesivir and favipiravir for mild to moderate COVID-19 disease.

Materials and Methods: A retrospective, observational and single-centre study was conducted at a COVID-19 infection facility and private tertiary care hospital, Mumbai, Maharashtra, India. Data of patients admitted during the period of 1st June 2021 to 31st August 2021 was collected and analysed in the months of September 2021 and October 2021. Adults participants diagnosed to have COVID-19 infection, not requiring critical care or oxygen therapy were included in the study. Time to recovery from treatment onset and the need for treatment escalation were the primary outcome measures. Data was entered into Microsoft excel spreadsheet version 16 and analysed. Statistical analysis was carried out using Chi-square test for the significance of association between tabulated values of data for qualitative and categorical data. Two-tailed unpaired t-test and Analysis of Variance (ANOVA) was used for quantitative tabulated data.

Results: This study included 158 participants, grouped into remdesivir (n=63), favipiravir (n=30) and Mab (n=65) treatment groups. Gender distribution was comparable in all groups (p-value=0.08). The three groups were compared for need of treatment escalation and time of recovery. The Mab treatment group (on comparing with other treatment arms) had earlier symptom recovery when given to patients with mild COVID-19 disease (p-value=0.006 for major symptoms) or when treatment was started within five days of symptom onset (p-value <0.001). Patients in Mab treatment group with mild illness required no treatment escalation compared to other groups (p-value=0.011). However, time to recovery patients in all treatment groups was comparable in case of patients with moderate COVID-19 illness (p-value=0.7381). In patients with moderate COVID-19 illness Mab treatment group required more frequent treatment escalation compared to remdesivir treatment group (p-value=0.044), when treatment was started within 5 days of symptom onset remdesivir and mab were comparable for treatment escalation (p-value=0.144). Vaccination status of the three groups differed significantly (p-value=0.033) hence a further subanalysis was done. On further analysis, non vaccinated patients receiving Mab recovered from minor symptoms (p-value=0.0006) earlier than those receiving Remdesivir. Amongst the participants of the Mab treatment-group, vaccinated and non-vaccinated patients had comparable recovery time and need for treatment escalation (p-value=0.57 and p-value=0.76, respectively). Participants who received Mab-treatment within five days of symptom onset; recovered earlier compared to those who received Mab treatment after five days (p-value=0.019).

Conclusion: Monoclonal antibody treatment group compared to the other treatment groups had earlier recovery in non vaccinated patients, mild COVID-19 disease, and when treatment was started before or on the 5th day of symptom onset.