COVID-19 Monoclonal Antibody Treatment Reduced Relative Hospitalizations by 60%

Mayo Clinic researchers reported in a study published in The Lancet's EClinicalMedicine on August 30, 2021, that the combination of two monoclonal antibody treatments known as REGN-CoV keeps high-risk patients out of the hospital when infected with mild to moderate COVID-19.

'Among high-risk patients with mild to moderate COVID-19, the REGEN-CoV (casirivimab–imdevimab) treatment was associated with a significantly lower rate of hospitalization.

Nearly 1,400 Mayo Clinic patients were enrolled in this observational study, with 696 receiving the casirivimab and imdevimab drug combo between December 2020 and April 2021 at Mayo Clinic sites in Arizona, Florida, Minnesota, and Wisconsin.

At each review point, the numbers for hospitalization were significantly lower in the REGEN-COV treated group.

• On Day 14, 1.3% of the treated group was in the hospital, compared to 3.3% of those who had not been treated.
• On Day 21, only 1.3% treated was hospitalized, compared to 4.2% of those who had not been treated.
• At the end of 28 days, 1.6% of those treated were hospitalized versus 4.8% of those who had not been treated.

This translated to 60%–70% relative reduction in hospitalization among treated patients.

"This real-world study suggests that when patients who are at high risk due to a range of comorbidities contract a mild or moderate case of COVID-19, this combination of monoclonal injections gives them a chance of a nonhospitalized recovery. In other words, they recover safely at home," says Raymund Razonable, M.D., a Mayo Clinic infectious diseases specialist and senior author of the study, in a press statement.

"Our conclusion overall at this point is that monoclonal antibodies are an important option in treatment to reduce the impact of COVID-19 in high-risk patients," says Dr. Razonable.

Mayo Clinic funded and conducted this study in collaboration with Nference Inc. No conflicts of interest were disclosed.

The Mayo Clinic is a nonprofit organization committed to innovation in clinical practice, education and research, and providing compassion, expertise, and answers to everyone who needs healing. 

Note: the U.S. FDA revised the emergency use authorization for REGEN-COV (casirivimab and imdevimab, administered together), authorizing REGEN-COV on August 10, 2021, for emergency use as post-exposure prophylaxis (prevention) for COVID-19 in 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.

REGEN-COV is not authorized for pre-exposure prophylaxis to prevent COVID-19 before being exposed to the SARS-CoV-2 virus -- only after exposure to the virus.