Treating COVID-19 Infection with the Monoclonal Antibody Sotrovimab
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Reviewed & Translated by Dat Tien Nguyen, B.A, ScM.
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Posted on March 30th, 2026
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Monoclonal antibodies had been proven to be effective at treating SARS-CoV-2 infection; however, mutations to the virus spike protein had resulted in significant resistance. For example, the appearance of the Omicron BA.1 variant had rendered existing treatments such as casirivimab & imdevimab less effective. Recently, Lancet had published a study that examined the effectiveness of sotrovimab at treating COVID-19.
Funding Source(s): United Kingdoms Medical Research Council
The clinical research included 1723 participants with an average age of around 70 years old, who had been hospitalized due to COVID-19 infection. On average these patients had experienced symptoms for around 6 days, and they have been hospitalized for around 2 days. 62% of them were treated with simple oxygen, 20% under some forms of non-invasive ventilation, and invasive mechanical ventilation was administered for 4% of them. Corticosteroid was used in 90% of the patients, with the percentage of those treated with remdesivir and tocilizumab being lowered at around 36% and 16%, respectively.
Besides the standard of care, these patients were randomly assigned to be treated intravenously with either placebo or sotrovimab. The monoclonal antibody was administered once at a dose of 1 g, which is doubled the approval dose of 500 mg. Sotrovimab works by binding to the spike protein expressed on the surface of the SARS-CoV-2 virus. This interaction would prevent the subsequent entry and infection.
After 28 days post treatment, the researchers found sotrovimab is effective at reducing the risk of death by 25% in patients who have a high level of SARS-CoV-2 antigen, indicating higher viral load. Subsequent analyses found that the clinical benefit of sotrovimab is limited to severe cases, as patients with lower levels of antigen did not experience the reduced risk of death. Despite this effectiveness, clinicians should be vigilant over the development of resistance variants; therefore, the continued development of new monoclonal antibodies is still needed.
Funding Source(s): United Kingdoms Medical Research Council
The clinical research included 1723 participants with an average age of around 70 years old, who had been hospitalized due to COVID-19 infection. On average these patients had experienced symptoms for around 6 days, and they have been hospitalized for around 2 days. 62% of them were treated with simple oxygen, 20% under some forms of non-invasive ventilation, and invasive mechanical ventilation was administered for 4% of them. Corticosteroid was used in 90% of the patients, with the percentage of those treated with remdesivir and tocilizumab being lowered at around 36% and 16%, respectively.
Besides the standard of care, these patients were randomly assigned to be treated intravenously with either placebo or sotrovimab. The monoclonal antibody was administered once at a dose of 1 g, which is doubled the approval dose of 500 mg. Sotrovimab works by binding to the spike protein expressed on the surface of the SARS-CoV-2 virus. This interaction would prevent the subsequent entry and infection.
After 28 days post treatment, the researchers found sotrovimab is effective at reducing the risk of death by 25% in patients who have a high level of SARS-CoV-2 antigen, indicating higher viral load. Subsequent analyses found that the clinical benefit of sotrovimab is limited to severe cases, as patients with lower levels of antigen did not experience the reduced risk of death. Despite this effectiveness, clinicians should be vigilant over the development of resistance variants; therefore, the continued development of new monoclonal antibodies is still needed.