The US FDA has expanded the Emergency Use Authorization (EUA) for the monoclonal antibody cocktail of casirivimab and imdevimab to also include emergency use for post-exposure prophylaxis of individuals exposed to COVID-19 and who are:

• not fully vaccinated or who are not expected to mount an adequate immune response to complete SARS-CoV-2 vaccination (for example, individuals with immunocompromising conditions including those taking immunosuppressive medications) and
• have been exposed to an individual infected with SARS-CoV-2 consistent with close contact criteria per Centers for Disease Control and Prevention (CDC) or
• who are at high risk of exposure to an individual infected with SARSCoV-2 because of occurrence of SARS-CoV-2 infection in other individuals in the same institutional setting (for example, nursing homes, prisons).

This new approved indication is applicable to adults and children (aged 12 years or older and weighing at least 40 kg) who are at high risk for progression to severe COVID-19, including hospitalization or death. The two monoclonal antibodies (casirivimab 600 mg and imdevimab 600 mg) are to be administered together by either intravenous infusion or subcutaneous injection.

The regulatory authority has specified that these monoclonal antibodies are not authorized for pre-exposure prophylaxis i.e. they are not to be used to prevent Covid-19. They are also not a substitute for vaccination. Those who are at high risk of ongoing exposure, repeat doses of 300 mg of casirivimab and 300 mg of imdevimab can be administered once a month for the duration of ongoing exposure.

Casirivimab and imdevimab are recombinant human IgG1 monoclonal antibodies that target the receptor binding domain (RBD) of the spike protein of SARS-CoV-2. The combination of the two antibodies is already FDA-approved for the treatment of mild to moderate Covid-19 in adults and children (≥12 years weighing at least 40 kg) who have tested positive for  SARS CoV-2 and are at high risk for progressing to severe COVID-19 and/or hospitalization. But, they are not approved for treatment of:

• Adults or pediatric patients who are hospitalized due to Covid-19, or
• Adults or pediatric patients who require oxygen therapy due to Covid-19, or
• Adults or pediatric patients who require an increase in baseline oxygen flow rate due to Covid-19 in those patients on chronic oxygen therapy due to underlying non-Covid-19-related comorbidity.

(Source: US FDA, July 30, 2021)

Dr Veena Aggarwal

Consultant Womens’ Health

MD and Chairperson, IJCP Group & Medtalks

Trustee, Dr KK’s Heart Care Foundation of India