REGEN-COV: Antibody therapy shows long-term protection against COVID-19

Regeneron Pharmaceuticals said on Monday a single dose of its antibody cocktail reduced the risk of contracting COVID-19 by 81.6% in the two to eight months period since the administration of the drug in a late-stage trial.

The new analyses show REGEN-COV reduced the risk of contracting COVID-19 (i.e., laboratory-confirmed symptomatic SARS-CoV-2 infections) by 81.6% during the pre-specified follow-up period (months 2-8), maintaining the 81.4% risk reduction during the first month after administration, which was previously reported in The New England Journal of Medicine.

“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., who leads the monoclonal antibody efforts for the NIH-sponsored COVID Prevention Network (CoVPN) and is 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.”

In results previously published, the trial met its primary endpoint, reducing the risk of COVID-19 (i.e., laboratory-confirmed symptomatic SARS-CoV-2 infections) by 81.4% within 1 month of receiving REGEN-COV.

The new results released today describe a pre-specified analysis for the following 7 months, throughout which an additional 45 symptomatic infections occurred. During this time period, REGEN-COV continued to prevent infection, without requiring additional doses. Compared to placebo (n=842), people who received a single dose of REGEN-COV (n=841) experienced:

81.6% reduced risk of developing COVID-19 during the pre-specified follow-up period, between months 2-8.

81.5% reduced risk of developing COVID-19 at any time during the 8 months after receiving REGEN-COV.

During the 8-month assessment period, 0 individuals in the REGEN-COV group were hospitalized due to COVID-19, compared to 6 individuals in the placebo group (1 person in the first month; 5 people during months 2-8). There were no deaths due to COVID-19 in any treatment group during the 8-month assessment period, and there were no new safety signals identified for REGEN-COV.

The trial, which was fully enrolled in early 2021, allowed participants to become vaccinated if they wished once the primary efficacy treatment period (month 1) was complete. Vaccination rates during the months 2-8 assessment period were balanced, with 34.5% (n=290) of the REGEN-COV group and 35.2% of the placebo group receiving at least 1 COVID-19 vaccine dose by the end of the 8-month assessment period.