COVID-19 Administration of Single-Dose Subcutaneous Anti- Spike(s) SARS-CoV-2 Monoclonal Antibodies Casirivimab and Imdevimab in High-Risk Pediatric Participants Under 12 Years of Age

The primary objective of the study is to characterize the concentrations of casirivimab+imdevimab in serum over time after a single subcutaneous (SC) administration The secondary objectives of the study are: * To assess the safety and tolerability of SC or single administration of casirivimab+imdevimab * To assess the occurrence of grade ≥3 injection site reactions and grade ≥3 hypersensitivity reactions, in participants treated with SC doses of casirivimab+imdevimab * To assess the immunogenicity of casirivimab+imdevimab