COVID-19, Pre- & Post-exposure Prophylaxis

by Michael S. Saag, M.D. last updated 2022-10-05 15:05:15.425332-04:00 © Antimicrobial Therapy, Inc.

COVID-19 Prophylaxis


  • Primary prevention / pre-exposure prophylaxis for at risk individuals
    • Evusheld (tixagevimab + cilgavimab), administered as two separate consecutive intramuscular injections (one injection per monoclonal antibody, given in immediate succession; Tixagevimab 300 mg/1.5 mL IM (single dose) + Cilgavimab 300 mg/1.5 mL IM (single dose)), may only be used as PRE-exposure prophylaxis for adults and pediatric individuals (12 years of age and older weighing at least 40 kg) who are not currently infected with SARS-CoV-2 and who have not recently been exposed to an individual infected with SARS-CoV-2, and who have:
      • Moderate to severely compromised immune systems due to a medical condition or due to taking immunosuppressive medications or treatments and may not mount an adequate immune response to COVID-19 vaccination (examples of such medical conditions or treatments can be found in the fact sheet for health care providers) or
      • A history of severe adverse reactions to a COVID-19 vaccine and/or component(s) of those vaccines, therefore vaccination with an available COVID-19 vaccine, according to the approved or authorized schedule, is not recommended.
    • Evusheld is approved through an EUA for pre-exposure prophylaxis, but is NOT approved for post-exposure prophylaxis nor for treatment of active, current SARS-CoV-2 infection
    • In the pivotal, RC clinical trial, Evusheld recipients had a  77% reduced risk of developing COVID-19 compared to those who received a placebo.  The estimated durability of Evusheld is up to 6 months protection.
    • Note:  Evusheld is active against most variants of SARS-CoV-2 (including most Omicron Variants, e.g., BA -4 and BA-5), however it does not have much activity against Omicron BA-6 variant.  


  • Primary prevention / post-exposure prophylaxis for previously uninfected household contacts:
    • REGEN-COV, administered 1200 mg as REGEN-COV (600 mg Casirivimab + 600 mg Imdevimab ) subcutaneously one time, OR  Bamlanivimab (700 mg) and etesevimab (1400 mg), administered intravenously together, may only be used as post-exposure prophylaxis for adults and pediatric individuals (12 years of age and older weighing at least 40 kg) who are:
      • At high risk for progression to severe COVID-19, including hospitalization or death and
      • Not fully vaccinated or who are not expected to mount an adequate immune response to complete SARS-CoV-2 vaccination (for example, people 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 SARS-CoV-2 because of occurrence of SARS-CoV-2 infection in other individuals in the same institutional setting (for example, nursing homes or prisons)
    • Relative risk reduction 81.4% relative risk reduction in COVID-19 infection (N Engl J Med, Aug 4, 2021)
    • NOT active against Omicron or BA-4 / 5 variants

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