Antibody treatment could reduce risk of hospitalisation and death for some Covid-19 patients

The World Health Organization (WHO) has recommended that Covid-19 patients who are at high risk of hospital admission or are severely ill with no natural antibodies to the virus receive a combination of antibodies as treatment.

The two antibodies, casirivimab and imdevimab, are monoclonal antibodies that when used together bind to the SARS-CoV-2 spike protein, neutralising the virus’s ability to infect cells.

During three clinical trials, the antibodies were found to potentially reduce the risk of hospitalisation and duration of symptoms in those at highest risk of severe disease, such as unvaccinated, older, or immunosuppressed patients. However, these trials are yet to be peer reviewed.

The RECOVERY trial similarly found that the combination of antibodies probably reduces deaths (ranging from 49 fewer per 1,000 in the severely ill to 87 fewer in the critically ill) and the need for mechanical ventilation in patients with no natural antibodies (seronegative).

The BMJ note that for all other Covid-19 patients, any benefits of this antibody treatment are unlikely to be meaningful.

New variants could reduce the treatment’s effect

The treatments have been recommended by a WHO Guideline Development Group (GDG), a panel of international experts and patients as part of a living guideline.

The panel acknowledged several cost and resource implications associated with this treatment, which may make access for low- and middle-income countries challenging.

For example, rapid serological tests will be needed to identify eligible patients who are severely ill, treatment must be given intravenously using specialist equipment, and patients should be monitored for allergic reactions.

They also recognise the possibility that new variants may emerge in which casirivimab and imdevimab antibodies may have reduced effect.

However, they say given the demonstrated benefits for patients, “the recommendations should provide a stimulus to engage all possible mechanisms to improve global access to the intervention and associated testing.”