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August 04, 2021

Regeneron's COVID-19 antibody cocktail can now be offered as a preventive measure, the FDA says

Monoclonal antibodies are laboratory-made proteins that boost the immune system’s ability to fight off viruses

Health News COVID-19
Regeneron antibody cocktail expanded use Kristoffer Tripplaar/Sipa USA

Regeneron's casirivimab and imdevimab are specifically directed against the spike protein of COVID-19 to block the virus’ attachment and entry into cells.

The U.S. Food and Drug Administration has expanded the use of Regeneron's monoclonal antibody COVID-19 treatment to include prevention after exposure to the virus.

If you have been exposed to SARS-CoV-2 and either haven't been vaccinated, or are vaccinated but still at high risk of severe illness, you can now be given the antibody cocktail to prevent infection. The first injection must be administered within 96 hours of exposure.

Those at most risk of developing severe illness despite vaccination are the 3% of Americans who are immunocompromised, including those with autoimmune diseases, HIV patients, cancer patients and organ transplant recipients. Studies have shown that many people with weakened immune systems do not produce coronavirus antibodies after receiving the COVID-19 vaccine.

The antibody cocktail was also approved for repeat dosing for people in high exposure risk settings such as nursing homes and prisons.

The monoclonal antibodies are able to prevent severe illness by attacking the infection while it is still in the nose and throat, Myron Cohen, a University of North Carolina at Chapel Hill researcher who was involved in the study of the drug, told NBC News. This is the first injectable COVID-19 antibody treatment to be approved for preventing the coronavirus post-exposure.

"It’s a race between your ability to make an antibody to protect your lungs and the rest of your body and the virus," he said. "And if you’re likely to lose the race, you’re the person for whom these antibody drugs are appropriate."

The FDA emphasizes that the expansion of the emergency authorization does not mean the antibody cocktail can be used as a substitute for the vaccine. All people who are eligible should still get vaccinated.

Under the original emergency use authorization to treat mild and moderate COVID-19 disease, the monoclonal antibody treatment had to be administered through an IV fusion, which limited its use.

Monoclonal antibodies are laboratory-made proteins that duplicate the immune system’s ability to fight off viruses. Regeneron's casirivimab and imdevimab are specifically directed against the spike protein of COVID-19 to block the virus’ attachment and entry into cells.

The FDA's expanded authorization is based on the findings of a large Phase 3 clinical trial. Participants who lived in a household with someone who had tested positive for SARS-CoV-2 were randomly assigned to either receive one injection of the Regeneron cocktail or a placebo.

According to the study's findings, the antibody injection reduced the risk of infection by 81%. Almost 8% of those in the placebo group developed COVID-19 symptoms within four weeks compared with just 1.5% of those who had received the preventive treatment. And when infection still occurred, those who received the antibodies had milder symptoms.

No one who received the antibody injection needed to visit the emergency department or be hospitalized, but 10 people in the placebo arm of the trial did.

Multiple studies have confirmed that the Regeneron monoclonal antibody cocktail is effective against all major COVID-19 variants of concern, including the Delta variant.

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