Regeneron's Antibody Cocktail Injection Prevents Symptomatic COVID-19 Among Individuals Exposed to SARS-CoV-2

The first Phase 3 trial (2069A) assessed the ability of REGEN-COV to reduce the risk and burden of COVID-19 infection among household contacts of SARS-CoV-2 infected individuals. The trial showed that REGEN-COV 1,200 mg administered SC reduced the risk of symptomatic infections by 81% in those who were not infected when they entered the trial. The Phase 3, double-blind, placebo-controlled trial assessed the effect of REGEN-COV on uninfected individuals without anti-SARS-CoV-2 antibodies or any COVID-19 symptoms, who lived in the same household as an individual who tested positive for SARS-CoV-2 within the prior four days. The trial enrolled 1,505 people who were not infected with SARS-CoV-2 at baseline and randomized to receive either one dose of REGEN-COV (1,200 mg) or placebo, administered as SC injections. On average, individuals treated with REGEN-COV who experienced a symptomatic infection resolved their symptoms in 1 week, compared to 3 weeks with placebo. Infected individuals also cleared the virus faster with REGEN-COV.

The second Phase 3 trial (2069B) of recently infected asymptomatic COVID-19 patients, for evaluating REGEN-COV 1,200 mg administered via SC administration found that REGEN-COV reduced the overall risk of progressing to symptomatic COVID-19 by 31% (primary endpoint), and by 76% after the third day. The trial also demonstrated that REGEN-COV shortened symptom duration and markedly reduced viral levels. The trial enrolled 204 individuals without any COVID-19 symptoms who tested positive for SARS-CoV-2 but did not have anti-virus antibodies at baseline, and were randomized to receive either one dose of REGEN-COV (1,200 mg) or placebo.


The trial met all primary and key secondary endpoints. In addition to reducing the risk of symptomatic infections, the total number of weeks patients experienced symptoms was nearly cut in half (45%) with REGEN-COV, and the viral burden was reduced by more than 90%. While not included in the initial analysis plan, researchers also found that 0 REGEN-COV patients and six placebo patients were either hospitalized or visited the emergency room because of COVID-19 during the 29-day efficacy assessment period.

"These data suggest that REGEN-COV can complement widespread vaccination strategies, particularly for those at high risk of infection. Importantly, to date REGEN-COV has been shown in vitro to retain its potency against emerging COVID-19 variants of concern," said Myron 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. "Despite standard precautions to reduce transmission, nearly 10% of unvaccinated individuals living with an infected person developed symptomatic infections if they did not receive REGEN-COV. If authorized, convenient subcutaneous administration of REGEN-COV could help control outbreaks in high-risk settings where individuals have not yet been vaccinated, including individual households and group living settings."

"COVID-19 transmission often occurs via infected people who do not yet have symptoms, so it is critical that we rapidly diagnose and treat these individuals for their own health and to prevent transmission," said Katharine Bar, M.D., co-principal investigator of the trial and Assistant Professor of Medicine, Infectious Diseases, Hospital of the University of Pennsylvania. "These data pave the way for REGEN-COV to be used before patients become symptomatic, with a more convenient subcutaneous administration."

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Regeneron Pharmaceuticals, Inc.