Sotrovimab, sold under the brand name Xevudy, is a human neutralizing monoclonal antibody with activity against severe acute respiratory syndrome coronavirus 2, known as SARS-CoV-2. It is under development by GlaxoSmithKline and Vir Biotechnology, Inc. Sotrovimab is designed to attach to the spike protein of SARS-CoV-2.The most common side effects include hypersensitivity (allergic) reactions and infusion-related reactions. Medical uses
In the European Union, sotrovimab is indicated for the treatment of COVID-19 in people aged twelve years of age and older and weighing at least 40 kilograms (88 lb) who do not require supplemental oxygen and who are at increased risk of the disease becoming severe.Sotrovimab is given by intravenous infusion, preferably within 5 days of onset of COVID-19 symptoms. Development and mechanism of action
Sotrovimabs development began in December 2019, at Vir Biotechnology when Vir scientists first learned of the initial COVID-19 outbreak in China. Vir subsidiary Humabs BioMed had already compiled a library of frozen blood samples from patients infected with viral diseases, including two samples from patients infected with SARS-CoV-1. Vir scientists obtained samples of the novel SARS-CoV-2 virus and mixed them with various antibodies recovered from the old SARS-CoV-1 blood samples. The objective was to identify antibodies effective against both SARS-CoV-1 and SARS-CoV-2. This would imply that the antibodies were targeting highly conserved sequences and in turn would be more likely to remain effective against future variants of SARS-CoV-2.
Pemphigus foliaceus is an autoimmune blistering disease (bullous disorder) of the skin. Pemphigus foliaceus causes a characteristic inflammatory attack at the subcorneal layer of epidermis, which results in skin lesions that are scaly or crusted erosions with an erythematous (red) base. Mucosal involvement is absent even with widespread disease.If there is an autoimmune IgG buildup in the epidermis, then nearly all of the antibodies are aimed against desmoglein 1. The effect of the antibodies and the immunological pathway is most likely one of three mechanisms:

Steric hindrance of the desmoglein 1: The antibody caps off the site for intracellular binding to another keratinocyte. Activation of an endocytic pathway: The antibody activates a pathway which causes an internalization of desmogleïn 1, which in turn causes a loss of adhesion. Disruption of function: In this case, the antibody blocks the desmoglein 1 from being formed into a desmosome. This in turn causes a loss of adhesion with acantholysis as a result. Cause
The National Institute of Arthritis and Musculoskeletal and Skin Diseases describes it like this:
Normally, our immune system produces antibodies that attack viruses and harmful bacteria to keep us healthy. In people with pemphigus, however, the immune system mistakenly attacks the cells in the epidermis, or top layer of the skin, and the mucous membranes. The immune system produces antibodies against proteins in the skin known as desmogleins. These proteins form the glue that keeps skin cells attached and the skin intact.