Neutralizing monoclonal antibodies for the prevention of severe COVID-19: a retrospective study during Omicron BA.1 variant surge.

Among treatment options for Coronavirus disease 2019 (COVID-19), monoclonal antibodies (mAbs) showed to be effective in preventing disease progression, but real-world data during the Omicron variant surge are still lacking. Multicentre retrospective study evaluating the effectiveness of sotrovimab and casirivimab-imdevimab in fragile patients with mild SARS-CoV-2 infection between November 2021 and March 2022. Unfavourable outcome was defined as increased need for oxygen supplementation and/or death. Of 268 study-participants, 12 (4.48%) previously needed supplemental oxygen, while 6 (2.24%) had active solid neoplasia (2.24%); 186 (69%) have previously received SARS-CoV-2 vaccination. Overall, 22 (8%) had unfavourable outcomes (42% versus 6% of patients with and without previous oxygen need and 50% versus 7% of patients with and without active solid neoplasia). Both supplemental oxygen therapy before SARS-CoV-2 infection and solid malignant tumour have shown to be risk factors for treatment failure. Log-rank test did not identify differences between sotrovimab and casirivimab-imdevimab treatment. Despite diffusion of Omicron variant, the rate of unfavourable outcome was higher than expected. The presence of underlying risk factors, including solid cancer and previous oxygen therapy are independently associated with risk of COVID-19 progression, suggesting the need for antiviral treatments not limited to mAbs and implementation of vaccine campaign.