Phase 3 Data Shows REGEN-COV Provides Long-Term Protection Against COVID-19

Regeneron Pharmaceuticals, Inc. announced this morning that a dose of REGEN-COV reduced the risk of contracting COVID-19 by up to 81.6% during the 8-month study period.

Regeneron and the National Institute of Allergy and Infectious Diseases (NIAID) reported positive results from their joint phase 3 trial, in which they administered 1200 mg of REGEN-COV in 4 subcutaneous injections.

"Today's new data demonstrate how a single dose of REGEN-COV can help protect people from COVID-19 for many months after administration," said Myron S. Cohen, M.D., leader of the monoclonal antibody efforts for the COVID-19 Prevention Network (CoVPN) and Director of the Institute for Global Health & Infectious Diseases at the University of North Carolina at Chapel Hill. "These results demonstrate that REGEN-COV has the potential to provide long-lasting immunity from SARS-CoV-2 infection, a result particularly important to those who do not respond to COVID-19 vaccines including people who are immunocompromised."

REGEN-COV reduced the risk of contracting symptomatic COVID-19 by 81.4% during the first month after administration and 81.6% during the 2-8 months following the injections.

During the trial, 841 participants were given REGEN-COV and 842 were given placebo. Comparatively, the REGEN-COV recipients had 81.5% reduced risk of developing COVID-19 at any time during the 8 months after administration, with 108 COVID-19 infections in the placebo group and 20 among the REGEN-COV group. No individuals were hospitalized with COVID-19, compared to the 6 hospitalizations in the placebo group.

After 1 month of the trial, 34.5% of the REGEN-COV group and 35.2% of the placebo group opted to receive at least one dose of a COVID-19 vaccine.

REGEN-COV is a combination of 2 monoclonal antibodies, casirivimab and imdevimab, designed specifically to block infectivity of SARS-CoV-2. The virus-neutralizing antibodies bind to the critical receptor binding domain of the virus’s spike protein, ensuring mutant viruses are treated and spike variants are diminished.

REGEN-COV is not US Food and Drug Administration (FDA) approved, but it has been approved for the treatment and post-exposure prophylaxis in specific populations designated high-risk.