• Monoclonal Antibody Treatments Authorized for COVID-19

    On July 30, the FDA has expanded the EUA for the COVID-19 monoclonal antibody therapeutic REGEN-COV (casirivimab and imdevimab) to include post-exposure prophylaxis, which includes known exposure without positive test. Post-exposure prophylaxis is authorized for the adults and adolescents (12 years of age and older) who are:

    1. At high risk for severe disease. 
    2. Either not fully vaccinated or immunocompromised and expected to not mount an adequate immune response to the vaccine.

    Eligible individuals must have either been exposed to an individual infected with SARS-CoV-2 (e.g. close contact per CDC) or at high risk of exposure due to COVID-19 infections in other individuals in the same setting (e.g. long term care facilities and correctional facilities). 

    How to Access and Administer

    Casirivimab plus imdevimab may be administered as either subcutaneous injection or a single IV infusion. Refer to the updated updated Fact Sheets for full details about dosing and administration. Combatcovid.org can help you ensure rapid access to monoclonal antibody treatment for your high-risk COVID-19 patients. Use their toolkit and support resources for administering the antibodies. 

    This new authorized use is in addition to the prior authorization of REGEN-COV to treat non-hospitalized patients with mild to moderate COVID-19 in adult and pediatric patients, aged 12 and older, with positive results of direct SARS-CoV-2 viral testing, and who are at high risk for progression to severe COVID 19, including hospitalization or death.

    NOTE: Post-exposure prophylaxis with REGEN-COV is not a substitute for vaccination against COVID-19, and REGEN-COV is not authorized for pre-exposure prophylaxis. Full vaccination combined with use of masks and other mitigation strategies are the best way to end the pandemic.


    The FDA has issued Emergency Use Authorization (EUA) for several monoclonal antibody treatments to prevent hospitalization from COVID-19. As of 6/25/21, given the impact of COVID-19 variants, only the combined casirivimab and imdevimab is available for use. A brief overview is provided below. For additional information, see these clinician handouts:

    All treatments are neutralizing IgG1 monoclonal antibodies that bind to the receptor binding domain of the spike protein of SARS-CoV-2.They are investigational drugs and not currently approved for any indication. The data supporting the EUA for casirivimab/imdevimab was based on an interim analysis from a phase two randomized, double-blind, placebo-controlled clinical trial in non-hospitalized adults with mild to moderate COVID-19 symptoms. The EUAs for sotrovimab and the combined treatment with bamlanivimab/etesevimab were based on phase III clinical trial data showing a reduction in hospitalizations in patients with mild to moderate COVID-19 symptoms. 

    All treatments have been authorized for use by clinicians in an outpatient setting to treat mild to moderate COVID-19 in adults and pediatric patients with positive results of direct SARS-CoV-2 viral testing who are 12 years of age and older weighing at least 40 kg, and who are at high risk for progressing to severe COVID-19 and/or hospitalization (e.g. body mass index (BMI) ≥35, chronic kidney disease, diabetes, immunosuppressed, over 65 years of age). The antibody treatments will need to be mixed and transfused at health care facilities with this capability. The treatments are most effective early in the course of infection so they will need to be prescribed and dispensed within 10 days of symptom onset.

    NOTE: bamlanivimab alone is not effective against the newer variants of SARS-CoV-2. The FDA has revoked its emergency use authorization for bamlanivimab alone. Read more. The combined treatment options of bamlanivimab/etesevimab and casirvimab/imdevimab are still available and authorized for use. Sotrovimab is another option that is available commercially under the conditions of the EUA. 

    The NIH treatment guidelines recommend use of bamlanivimab plus etesevimab, casirivimab plus imdevimab, or sotrovimab, for the treatment of outpatients with mild to moderate COVID-19 who are at high risk of clinical progression as defined by the EUA criteria. New information: the FDA has authorized changes in the doses for casirivimab plus imdevimab from 2400 mg to 1200 mg (600 mg casirivimab and 600 mg imdevimab). None of the treatments are authorized for use in patients who are hospitalized or experience anaphylaxis, and the ability to activate the emergency medical system (EMS), as necessary.

    Additional resources from HHS and ASPR include an allocation dashboard, distribution playbook, and information for clinicians.

    The treatment will be available with no out-of-pocket costs for patients. CPT codes will be issued for reimbursement of clinicians administering the infusion. CMS has released billing and payment guidance for Medicare beneficiaries.