Our COVID-19 Rapid
Response Program

Regeneron is applying our 30 years of scientific and technology expertise to combat the COVID-19 pandemic. We feel uniquely positioned to face this public health threat given our proprietary VelociSuite® technologies and our track record against infectious diseases such as Ebola.

Developing our Novel Anti-Viral Antibody Cocktail

Casirivimab and imdevimab form a novel monoclonal antibody cocktail being studied for its potential both to treat appropriate patients with COVID-19 and to prevent SARS-CoV-2 infection.

Casirivimab and imdevimab are investigational therapies and have been authorized by the FDA for the emergency use described below. Casirivimab and imdevimab must be administered together. Casirivimab and imdevimab are not FDA approved for any use. Safety and effectiveness of casirivimab and imdevimab have not been fully established for the treatment of COVID-19.

Our COVID-19-related discovery efforts started in early 2020, when we began producing hundreds of virus-neutralizing antibodies in our genetically-engineered mice and identifying similarly-performing antibodies from human COVID-19 survivors. By June, we had selected and progressed the two most potent and non-competing antibodies, casirivimab (REGN10933) and imdevimab (REGN10987), into large-scale manufacturing and clinical trials. In September and October, we announced data from the ongoing trial of non-hospitalized patients, which showed that our antibody cocktail significantly reduced viral load and the need for medical visits in mild to moderate patients.

Emergency Use Authorization for Our Antibody Cocktail

The Secretary of the Department of Health and Human Services has declared a public health emergency that justifies the emergency use of the unapproved product. This use is authorized only for the duration of the declaration that circumstances exist justifying the authorization of the emergency use under section 564(b)(1) of the Act, 21 U.S.C. § 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner.

Due to the COVID-19 public health emergency, this EUA will provide appropriate patients more ready access to this therapy. For information about the authorized use of the antibody cocktail and mandatory requirements of the EUA in the U.S., please review the FDA Letter of Authorization for the EUA here. Health care providers should also review the HCP fact sheet for mandatory requirements of the EUA and information on the authorized use of casirivimab and imdevimab, including the definition of high risk patients, Warnings and Precautions for Hypersensitivity, including anaphylaxis and infusion-related reactions and limitations of benefit and potential for risk in patients with severe COVID-19, as well as adverse reactions, including serious adverse reactions, and information about use in specific populations. Additionally, please refer to the Dear HCP Letter about the prevention of medical errors. A patient fact sheet is available for reference when discussing with patients. Casirivimab and imdevimab administered together are an unapproved investigational antibody combination therapy, and there are limited clinical data available.

Ongoing Clinical Research

The antibody cocktail of casirivimab and imdevimab is being studied in four late-stage clinical trials: two for the treatment of certain hospitalized and non-hospitalized (“ambulatory”) COVID-19 patients, the open-label RECOVERY trial of hospitalized COVID-19 patients in the UK, and a trial for the prevention of COVID-19 in uninfected people who are at high-risk of exposure to a COVID-19 patient (such as the patient’s housemate). The Phase 3 prevention trial is being jointly conducted with the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH).

The development and manufacturing of the antibody cocktail has been funded in part with federal funds from the Biomedical Advanced Research and Development Authority (BARDA), part of HHS, Office of the Assistant Secretary for Preparedness and Response, under OT number: HHSO100201700020C.

Read more about the clinical program here

Current & Anticipated Supply

The U.S. government has purchased the initial supply of the casirivimab and imdevimab antibody cocktail for use in non-hospitalized COVID-19 patients and has said it will provide these doses at no cost to patients, though healthcare facilities may charge fees related to the one-time/one-dose administration. The two government contracts bring the total potential U.S. volume of casirivimab and imdevimab to over 1.5 million doses, to be supplied before June 30, 2021.

The government is coordinating allocation of the antibody cocktail to state and territorial health departments. Patients, caregivers and healthcare providers can find sites with COVID-19 antibody treatments through the HHS or National Infusion Center Association locator tools.

Regeneron is also collaborating with Roche to increase global supply of casirivimab and imdevimab, with expected production of at least 2 million treatment doses per year, beginning in 2021. Regeneron is responsible for development and distribution of the treatment in the U.S., and Roche is primarily responsible for development and distribution outside the U.S.

Published Research


  • New England Journal of Medicine: “REGN-COV2, a Neutralizing Antibody Cocktail, in Outpatients with Covid-19” details initial clinical data from a seamless Phase 1/2/3 trial of the antibody cocktail in non-hospitalized patients with COVID-19, showing that casirivimab and imdevimab effectively reduced viral load and the need for medically-attended visits, with the greatest benefit in patients who had not yet mounted their own effective immune response or had high viral load at baseline.


Achieving immunity to SARS-CoV-2:

Get an overview of how anti-viral antibody medicines and vaccines are similar and different.

Download this pdf

Our technologies

From discovery to large-scale manufacturing, our VelociSuite® technologies provide unmatched precision and speed in developing targeted antibody medicines.

Learn about our technologies

COVID-19 Business Updates


Given the ongoing nature of this pandemic, we are regularly assessing any potential impact to our business, including aspects of product supply, clinical development and commercial operations. We will share material updates as warranted.

Our team:

Our priority is to protect the health and safety of our colleagues and ensure the continuity of our business. We are monitoring the pandemic situation closely and have established a senior response committee to assess our guidance continually. Currently, many of our colleagues are working from home if their job allows it. We have taken additional health and safety precautions to protect our critical laboratory and manufacturing colleagues whose jobs require they be on-site. These include alternating shift schedules to reduce density on-site, a mask requirement on campus, provision of masks and other personal protective equipment, health monitoring for on-site colleagues, and physical modifications to office and lab spaces. We are also providing regular testing for all colleagues working at our Tarrytown campus.

Clinical trials:

Regeneron conducts clinical trials in multiple countries across the world. We continue to evaluate the impact of the COVID-19 pandemic on an individual clinical trial basis and expect fully-recruited clinical studies to remain generally on track. After briefly pausing new enrollment in certain studies due to the pandemic, enrollment in both new and ongoing clinical studies started to resume as regions relaxed their restrictions and health care resources started to become more available for non-COVID-19 activities. However, there has been a resurgence of COVID-19 cases in many regions across the world, and any resurgence in the regions where we or our collaborators conduct clinical trials may require timeline adjustments for potentially impacted studies. We continue to work closely with regulators to follow recent Health Authority and Regulatory Agency issued guidance as they pertain to clinical trial operations.

Supply chain & market supply:

As a matter of practice, we are always working to ensure the stability of our supply chain and maintain adequate market supply for all commercialized products. We maintain adequate market supply for all our commercialized products, and our raw material supplies and contract manufacturing support have remained stable despite the current pandemic situation. In order to enable the U.S. manufacturing site to maximize production of casirivimab and imdevimab, we worked with regulatory authorities to accelerate licensing of our Irish facility to manufacture our full portfolio of commercial products.

Supporting our communities:

Regeneron’s community response focuses on raising critical funds, mobilizing resources and supporting the most vulnerable nonprofits, people and communities around the world. Through Regeneron’s COVID-19 Double Matching Gift Campaign, we supported our employees’ giving and select charities by raising $750,000. Locally, we are supporting Afya Foundation’s efforts to deliver critically needed medical supplies to qualified, New York-based health centers. In Rensselaer, we are supporting the Capital Region Community Foundation’s COVID-19 Response Fund, which provides flexible resources for nonprofits working with those who are disproportionately impacted. We are planning additional and expanded efforts to support people in need during this critical time and will share more details in this space.

Regeneron’s Industrial Operations and Product Supply (IOPS) team assisted New York State by making and donating viral transport media (VTM), a critical component of COVID-19 testing kits that has been in short supply. VTM is a liquid used to preserve patient test samples (a swab from the nose or throat) until they can be tested. Regeneron worked to obtain the necessary components, determined formulas and proportions to meet NYS-specifications, and leveraged the specialized skill set of our employees to make sterile VTM and place it into test tubes. We delivered over 500,000 total VTM kits to New York State and donated 100 percent of our supplies and labor for this effort, an approximately $1 million in-kind contribution. Learn more