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The US Food and Drug Administration on Saturday issued an emergency use authorization for Regeneron’s antibody cocktail to treat Covid-19 in high-risk patients with mild to moderate disease.

President Donald Trump received the therapy, called REGEN-COV2, when he was hospitalized for coronavirus. The treatment has to be infused into the bloodstream and is meant to mimic an immune response to infection.

The cocktail reduced Covid-19-related hospitalizations and emergency room visits in some patients within 28 days of treatment, the FDA said in a news release.

Regeneron’s chief executive officer, Dr. Leonard S. Schleifer, said in a statement that demand may initially exceed supply, “making it even more critical that federal and state governments ensure REGEN-COV2 is distributed fairly and equitably to the patients most in need.”

An emergency use authorization (EUA) is a lower regulatory bar than full approval by the FDA. An EUA allows products to be used under particular circumstances before all the evidence is available for approval.

“When used to treat COVID-19 for the authorized population, the known and potential benefits of these antibodies outweigh the known and potential risks,” the FDA said.

Regeneron submitted its application for the authorization in October, shortly after Trump tested positive for the coronavirus and received the biotechnology company’s antibody therapy.

“Regeneron now expects to have REGEN-COV2 treatment doses ready for approximately 80,000 patients by the end of November, approximately 200,000 patients by the first week of January, and approximately 300,000 patients in total by the end of January 2021,” the company said in a news release Saturday.

Treatment is for use early in infection

Unlike some other drugs used for Covid-19, the antibody cocktail is meant to be given early in infection, before patients are hospitalized or require oxygen therapy. The drug should be given as soon as possible after a positive viral test, according to the FDA.

The FDA’s authorization is limited to high-risk patients, like those who are older than 65 years of age or have a BMI greater than or equal to 35. Patients with other conditions like diabetes, cardiovascular disease or chronic kidney disease also qualify for the drug.

The authorization only applies to patients 12 years of age or older. The cocktail has not been authorized for use in patients who are hospitalized with Covid-19 or need oxygen therapy because of Covid-19.

Regeneron’s cocktail is a combination of two monoclonal antibodies, casirivimab and imdevimab, that are produced in a laboratory.

The antibodies target the spike protein the virus uses to drill into healthy cells. With two antibodies, the hope is to trap and shut down viral replication.

“The FDA remains committed to advancing the nation’s public health during this unprecedented pandemic. Authorizing these monoclonal antibody therapies may help outpatients avoid hospitalization and alleviate the burden on our health care system,” said FDA Commissioner Dr. Stephen Hahn in a statement.

Regeneron isn’t the only company that’s been working on antibody therapies for the coronavirus. There are more than 70 different antibody treatments for Covid-19 under investigation, according to BIO, an association that represents major biotechnology companies

Earlier this month, the FDA issued an emergency use authorization for another antibody treatment from pharmaceutical manufacturer Eli Lilly with similar conditions.

CNN’s Shelby Lin Erdman contributed to this report.