Gloved hands in laboratory, handling research instruments

An antibody cocktail authorized to halt disease progression in sick COVD-19 patients has been shown to prevent the disease altogether at a lower dose in healthy people.

Among study participants living with a person with a diagnosed infection, 81% showed a reduced risk of symptomatic infection after receiving the combination of casirivimab with imdevimab, drugmaker Regeneron reported Monday. Fully 31% of the participants were at high risk of severe COVID-19, and 38% were aged 50 years (ages ranged from 12 to 92 years).

Participants received 1,200 mg of the cocktail, REGEN-COV, via infusion. The preventive treatment “rapidly protected household contacts from exposure to SARS-CoV-2 at home, with 72% protection against symptomatic infections in the first week, and 93% in subsequent weeks,” the drugmaker announced.

What’s more, participants who did develop symptomatic infections cleared the virus faster and had shorter symptom duration than those in a placebo group, the company said. The cocktail currently is authorized as a treatment for mild COVID-19 cases in a larger, 2,400 mg IV dose, with infusion times of 20 minutes or more. 

The company plans to ask the Food and Drug Administration to approve its use as a preventive, according to CNBC. 

“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., an infectious disease expert who leads the monoclonal antibody efforts for the NIH-sponsored COVID Prevention Network.

The study was run jointly with the National Institute of Allergy and Infectious Diseases.