REGEN-COV was confirmed for continued use against COVID-19 cases deemed at high risk for progression to hospitalization or death last week, with the extension of its Emergency Use Authorization by the United States Food and Drug Administration (FDA).
The therapeutic is a monoclonal antibody cocktail developed by Regeneron Pharmaceuticals. It was and remains authorized to treat mild-to-moderate COVID-19 cases among adults and children at least 12 years old. To be utilized, these cases must demonstrate positive results from direct SARS-CoV-2 viral testing and be at high risk for progression to a severe case of the disease.
Whether used as a treatment or as a post-exposure prophylaxis, REGEN-COV is used as a mix of 600 mg of casirivimab and 600 mg of imdevimab administered together.
The approval followed studies that showed side effects restricted to, most commonly, injection site reactions among a small group of subjects. No life-threatening allergic reactions emerged during testing, and those who have had severe reactions are advised not to retake it. A randomized Phase 3 trial showed a single use of REGEN-COV capable of providing an 81 percent reduction in symptomatic COVID-19 cases, compared to placebos after 29 days.
In the overall trial population, the drug provided a 62 percent reduction in confirmed symptomatic COVID-19 cases.
FDA approval comes with major caveats and restrictions, however. For one thing, the treatment cannot be used as a prophylaxis to prevent COVID-19 before being exposed to the SARS-CoV-2 virus. It is meant to be used solely after exposure, nor, as the FDA stressed, is it meant as a substitute for vaccination. Likewise, it should not be used on the fully vaccinated.
The FDA added that REGEN-COV should be used in the case of post-exposure prevention only on those who are not expected to mount adequate immune responses to full SARS-CoV-2 vaccination, such as the immunocompromised. Potential users must have been exposed to individuals infected with the virus or are at high risk of exposure to such carriers.