Regeneron's Monoclonal Antibodies Are FDA-Authorized To Treat COVID-19


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Key Takeaways

  • The FDA issued emergency use authorization to Regeneron's monoclonal antibodies—casirivimab and imdevimab—for the treatment of COVID-19.
  • The treatment is only authorized for people with mild to moderate COVID-19 infections, not anyone who is hospitalized.
  • The antibodies must be administered together via IV.
  • President Trump received these antibodies during his COVID-19 infection.

On Friday, November 21, the Food and Drug Administration (FDA) authorized the use of Regeneron’s monoclonal antibody cocktail for the treatment of COVID-19. The drug, referred to as REGN-COV2, is the same one that President Trump received after being diagnosed with COVID-19 in early October. 

While President Trump was hospitalized for his case of COVID-19, the recent FDA emergency use authorization (EUA) is not intended for people already in the hospital with the disease or receiving oxygen therapy because of it. According to the FDA, the antibodies are currently authorized for the treatment of mild to moderate COVID-19, and can be administered to:

  • Adults, including adults over age 65 with chronic conditions 
  • Pediatric patients age 12 and older who weigh at least 40 kilograms (88 pounds)

To be eligible for REGN-COV2 treatment, the FDA says patients must have a positive SARS-CoV-2, the virus that causes COVID-19, test and be at high risk for progressing to severe COVID-19.

An emergency use authorization is different from an approval. The FDA issues an EUA when there is enough scientific evidence to show a drug has more benefit than risk in an emergency situation.

What's In The Drug?

Regeneron’s antibody cocktail is made up of two different monoclonal antibodies, casirivimab and imdevimab. The FDA EUA requires both to be administered together via intravenous (IV) infusion. 

A monoclonal antibody is a laboratory-made clone of a specific parent immune cell intended to fight infection in the body. Casirivimab and imdevimab work by blocking the spike protein of the SARS-CoV-2 virtus from attaching to receptors in human cells. 

To make these antibodies in a lab, Regneron scientists evaluated antibodies from people who had recovered from COVID-19 as well as human antibodies produced by mice. Wondering how that works? The scientists use mice that have been genetically modified to have a human immune system. 

How Do You Get It?

The FDA authorization says REGN-COV2 should be administered through an IV, but it is not indicated for hospitalized COVID-19 patients. This poses the question: How might you receive an IV outside of a hospital setting?

"The indication to give these antibodies to individuals who are not/have yet to be hospitalized certainly presents some logistical challenges," Aaron Emmel, PharmD, MHA, BCPS, founder and director of, tells Verywell via email. He says that ideally, the casirivimab/imdevimab combination could be administered right in your primary care provider's office. However, most PCP offices aren't set up to provide IV infusion therapy.

"This requires policies, procedures, and trained healthcare staff," he says. "Now is an especially difficult time for these practices to establish these processes when so many practices have been disrupted by COVID-19."

Ultimately, the way antibodies are administered will probably depend on where you live.

"I think you are going to see a significant disparity in where these drugs are given based mainly on how local healthcare ecosystems are designed throughout the country," Emmel says. "In areas with well established health systems, you may see some coordinated effort to direct patients to a local urgent care facility or hospital-based outpatient infusion center to receive treatment."

Aaron Emmel, PharmD, MHA, BCPS

You are going to see a significant disparity in where these drugs are given based mainly on how local healthcare ecosystems are designed throughout the country.

— Aaron Emmel, PharmD, MHA, BCPS

Emmel expects the use of antibody treatments in more rural areas will be quite different.

"You may see lower uptake of these treatments due to the logistical challenges, or more providers directing patients to emergency rooms," he says.

In the event that patients with mild to moderate COVID-19 symptoms are sent to the hospital to receive antibody treatment, Jason Reed, PharmD, says it's most likely they'll be sent to hospital infusion treatment facilities.

"These facilities are best suited to deal with these type of monoclonal antibodies that must be carefully mixed and handled gently during administration," Reed, founder of, tells Verywell via email. "The equipment required is already present in infusion treatment centers. Many outpatients come into these facilities already and can be easily segregated from others."

Reed adds that almost all hospitals have some sort of infusion treatment facility. "Some hospitals own more than one infusion treatment center and many have sites that are located in the community and not directly on the hospital campus," he says.

In some cases, travel nurses may be able to administer IV infusions at patients' homes. "This is a nice option, especially for someone who has mild or moderate COIVD-19 and needs to isolate anyway," Reed says.

How Effective Is It?

Data shows the combination of casirivimab and imdevimab can reduce viral load—the amount of SARS-CoV-2 circulating in a person's blood. A clinical trial of 799 non-hospitalized adults with mild to moderate COVID-19 symptoms showed treatment with REGN-COV2 lead to a greater viral load reduction after seven days compared to treatment with a placebo.

Among patients considered to be at a high risk for disease progression, only 3% of people treated with REGN-COV2 went on to be hospitalized or visit the emergency room, compared to 9% of people treated with a placebo.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Coronavirus (COVID-19) update: FDA authorizes monoclonal antibodies for treatment of COVID-19. Updated November 21, 2020.

  2. Regeneron. Regeneron's covid-19 outpatient trial prospectively demonstrates that regn-cov2 antibody cocktail significantly reduced virus levels and need for further medical attention. Updated October 28, 2020.

By Anisa Arsenault
Anisa joined the company in 2018 after managing news surrounding fertility, pregnancy, and parenting for The Bump. Her health and wellness articles have appeared in outlets like Prevention and Metro US. At Verywell, she is responsible for the news program, which includes coverage of COVID-19.