Sotrovimab is an antiviral monoclonal antibody treatment that works by sticking to the surface of the SARS-CoV-2 virus to stop it from replicating. Previous studies have shown that antiviral monoclonal antibody treatments can reduce the risk of hospitalisation and death in patients in the early stages of COVID-19 infection, and in some hospitalised patients without antibodies against the virus. However, these trials were conducted in patients who were mostly unvaccinated, so it was not known which, if any, current patients could benefit from treatment.
1,723 patients from 107 UK hospitals participated in the sotrovimab evaluation between January 2022 and March 2024. Over 80% of the patients were vaccinated and over 80% had COVID-19 antibodies present in their blood. Almost all of the participants were infected with an Omicron variant of COVID-19.
Key findings
- Sotrovimab reduced the risk of death within 28 days of randomisation by 25% in patients with high viral antigen levels, though there was substantial uncertainty about the size of benefit (rate ratio 0.75; 95% confidence interval 0.56 to 0.99, p=0.046); 82/355 (23%) of those allocated sotrovimab died versus 106/365 (29%) of those in the usual care group.
- No benefit was seen when considering all patients together regardless of their blood virus levels (high, low and unknown antigen levels). Among all patients, 177/828 (21%) of those allocated sotrovimab died versus 201/895 (22%) in the usual care group (rate ratio 0.95; 95% confidence interval 0.77 to 1.16; p=0.60).
A major limitation of monoclonal antibody therapies has been the frequent emergence of new variants of the virus that are resistant to treatment. The RECOVERY sotrovimab evaluation was the first directed at patients with the Omicron variant that became dominant in late 2021 and which was resistant to most other monoclonal antibodies in use. Although sotrovimab reduced the risk of death in some patients in RECOVERY, many recent SARS-CoV-2 variants have now developed resistance to sotrovimab, limiting its current effectiveness.
Read the full story on the Nuffield Department of Population Health (NDPH) website.