Regeneron says antibody cocktail cuts COVID-19 risk for up to eight months

Regeneron’s antibody cocktail cut the risk of contracting COVID-19 by 81.6 percent in the two to eight months after the cocktail’s administration, the pharmaceutical company announced on Monday. 

A single dose of the cocktail, a combination of the monoclonal antibodies casirivimab and imdevimab called REGEN-COV, involves four injections.

The phase three trial, conducted along with the National Institute of Allergy and Infectious Diseases (NIAID), showed the dose’s protection remained relatively stable since the 81.4 percent risk reduction reported in the first month.

Within the eight months, there were zero COVID-19 hospitalizations among those who received REGEN-COV, while six out of more than 800 people in the placebo group were admitted due to the virus. 

Myron Cohen, who heads the monoclonal antibody research for the National Institutes of Health’s (NIH) COVID-19 Prevention Network, said the data shows the cocktail “can help protect people” from the virus “for many months after administration.”

“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,” he said in a news release.

The study involved 841 REGEN-COV recipients and 842 in the placebo group — all of whom were uninfected and did not have COVID-19 antibodies. Participants were tested weekly during the first month, while in the two to eight month range they were tested only if they developed COVID-19 symptoms.

Researchers allowed participants to get vaccinated one month after the cocktail’s administration. In total, about 34.5 percent of the REGEN-COV recipients and 35.2 percent of the placebo group had at least one dose of the vaccine before the eighth month ended.  

The Food and Drug Administration granted Regeneron’s antibody cocktail an emergency use authorization for the treatment of mild to moderate COVID-19 symptoms in specific “high risk” individuals, including those infected but not hospitalized.

But the drug combination is not considered a replacement for the COVID-19 vaccine in the U.S. It cannot be administered to those hospitalized for COVID-19, those who require oxygen due to COVID-19, and those who require chronic oxygen therapy due to an underlying condition who need an increased oxygen flow rate because of the virus.

The results come as progress is being made in research on Pfizer’s and Merck’s oral COVID-19 treatment. Last week, Pfizer released data showing its pill reduced the risk of hospitalization and deaths by 89 percent. 

Merck’s pill, developed with Ridgeback Biotherapeutics, was found to decrease hospitalizations by 50 percent, prompting the company to apply for emergency use authorization.