Impact analysis of SARS-CoV-2 vaccination in patients treated with monoclonal antibodies: A monocentric experience

Background: Since the discovery of SARS-CoV-2, no treatment has been able to completely eradicate the virus. The study aimed to evaluate the virological and clinical impact of the vaccination in SARS-CoV-2 infected pa- tients treated with monoclonal antibodies (mAbs). Methods: This single-centre, observational, retrospective, real-life study was performed on SARS-CoV-2 symp- tomatic outpatients and inpatients treated with mAbs from March 2021 to November 2022 includes 726 patients. Each patient received available mAbs (bamlanivimab-etesevimab or casirivimab-indevimab or sotrovimab or tixagevimab-cilgavimab) according to the circulating virus strains. Age, comorbidities, vaccination status, death rates, duration of virological clearance, average length of stay, risk factors, and hospitalization or ICU admission were recorded. Results: Of 726 patients with complete data analyzed (median age 64), 516 outpatients and 210 inpatients were included. Vaccination status was known for all participants: 74.4 % and 51.7 % were vaccinated against SARS- CoV-2 among inpatients and outpatients, respectively. A shorter duration of virological clearance was observed in the vaccinated group, with a median of 16 days (IQR 15–17), compared to 19 days (IQR 18–21) in the un- vaccinated group [HR 1.21; p < 0.032]. Multivariate analysis of virological clearance also showed statistical significance with tixagevimab cilgavimab 300 mg/300 mg (HR 2.73, p value < 0.001). No significant difference was found in worsening [OR 1,29; p = 0.57] and mortality [OR 0.65; p = 0.81] rates between vaccinated and unvaccinated patients treated with mAbs. Conclusions: Key findings include a shorter duration of virological clearance in vaccinated outpatients but no significant differences in worsening or mortality rates between vaccinated and unvaccinated patients treated with mAbs. The study suggests a potential synergistic role of mAbs in accelerating virological clearance in vaccinated patients with mild to moderate COVID-19, with differing effects in hospitalized patients. Therefore, it is essential to implement health surveillance in high-risk patients with comorbidities in order to identify early any variants that might otherwise escape neutralizing antibodies.