Vaccine Info

REGEN-COV (Ronapreve) Monoclonal Antibody Cocktail

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Last reviewed
June 11, 2022

Regeneron REGEN-COV (Ronapreve; casirivimab-imdevimab) Anti-SARS-CoV-2 Monoclonal Antibody For 2022

Regeneron's REGEN-COV Anti-SARS-CoV-2 Monoclonal Antibody (Ronapreve) combines two monoclonal antibodies (mAbs), casirivimab, and imdevimab, explicitly designed to block the infectivity of SARS-CoV-2, the coronavirus that causes COVID-19. REGEN-COV was the first mAbs therapy to demonstrate an antiviral effect in patients hospitalized with COVID-19. Regeneron does not use human tissue in any of our manufacturing processes. Instead, the manufacture of mAbs starts with a mammalian cell line called the Chinese Hamster Ovary (CHO) cells. These CHO cells are then modified with a synthetic DNA sequence to direct them to make mAbs indistinguishable from human antibodies.

Regeneron core technologies enable the rapid and efficient generation of this protective antiviral mAbs outside of the body, derived from genetically humanized mice or convalescent humansRegeneron's potent, virus-neutralizing antibodies that form the REGEN-COV bind non-competitively to the critical receptor binding domain of the coronavirus's spike protein, which diminishes the ability of mutant viruses to escape treatment and protects against spike variants that have arisen in the human population, as detailed in Science, published on August 21, 2020. The resulting antibodies correspond to the most potent antiviral antibodies that could be elicited by a vaccine or exposure to a pathogen.

REGEN-COV can be delivered via injection or IV, providing 'passive immunity and immediately protecting people from COVID-19. However, it must be re-administered to remain effective over time. These mAbs can also treat an existing infection, unlike vaccines used preventatively.

The WHO announced on September 24, 2021, 'patients who are non-severe and at higher risk for hospitalization be treated and those that are severe or critical with seronegative status (those who have not developed natural antibodies against COVID-19 determined through accurate, rapid tests) be treated; as these two patient groups are the patients that stand to benefit most from the treatment.' On March 3, 2022, the WHO suggested treatment with casirivimab-imdevimab, conditional to those with seronegative status, and where viral genotyping can confirm a susceptible SARS-CoV-2 variant (i.e., excluding omicron BA.1). Treatment with casirivimab-imdevimab is in addition to the current standard of care, including corticosteroids and IL-6 receptor blockers.

The Company announced on October 14, 2021, that the FDA had accepted for priority review a Biologics License Application (BLA) for REGEN-COV to treat COVID-19 in non-hospitalized patients and as prophylaxis in specific individuals. A second BLA submission focusing on treating patients hospitalized due to COVID-19 is expected to be submitted later in 2021. The U.S. FDA issued emergency authorization on February 25, 2021. The FDA issued an updated Health Care Provider Fact Sheet for REGEN-COV on December 20, 2021, with specific information regarding expected activity against the Omicron variant (B.1.1.529/BA.1). On January 19, 2022, the U.S. NIH published an updated version of the statement that the COVID-19 Treatment Guidelines Panel addressed the dominance of the B.1.1.529 (Omicron) variant in the U.S.

The U.S. FDA revised the authorizations for REGEN-COV on January 24, 2022, to limit their use to only when the patient is likely to have been infected with or exposed to a variant that is susceptible to these treatments. Because data show that these treatments are highly unlikely to be active against the omicron variant. These treatments are not authorized in any U.S. states, territories, or jurisdictions. As of April 14, 2022, the FDA extended by three months its review of the BLA for REGEN-COV to treat COVID-19 in non-hospitalized patients and as prophylaxis in certain individuals. 

However, it remains authorized in Europe. On June 8, 2022, the EMA published a list of critical authorized medicines for the COVID-19 public health emergency.

DrugBank: DB15691; KEGG D11938D11939 Dosage and Administration (Section 2.4) and How Supplied/Storage and Handling (Section 19): updated storage temperature range and duration updated as of November 1, 2021.

Tarrytown, New York-based Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) collaborates with Roche to increase the global supply of REGEN-COV. Regeneron is responsible for developing and distributing the treatment in the U.S. Roche is primarily responsible for the development and distribution of Ronapreve outside the U.S. Regeneron's August 2021 corporate update is linked hereRegeneron's VelocImmune technology utilizes a proprietary genetically engineered mouse platform endowed with a genetically humanized immune system to produce optimized fully human antibodies. This COVID-19 Antibody Cocktail's development and manufacturing have been funded partially with federal funds from the Biomedical Advanced Research and Development Authority under O.T. number: HHSO100201700020C. Corporate Fact Sheet; Form 10K.

REGEN-COV Omicron BA.x Effectiveness 

On June 3, 2022, the Wiley Online Library published 'Clinical efficacy and in vitro neutralization capacity of monoclonal antibodies for SARS-CoV-2 delta and omicron variants.' In patients with delta variant infections treated with casivirimab/imdevimab, we observed a rapid decrease of respiratory viral RNA at day three after mAb therapy.'

The U.S. NIH's OpenData Portal reported REGEN-COV in vitro Therapeutic Activity. But, given the breaking nature of these releases, Omicron data should be interpreted with caution. Circulating SARS-CoV-2 coronavirus viral variants may be associated with resistance to monoclonal antibodies. The NIH published updated guidelines on February 1, 2022.

Under published UK policies, Ronapreve (casirivimab and imdevimab) will only be routinely accessed if genotyping confirm infection with a non-Omicron virus variant. The Company announced on December 16, 2021, that Regeneron's currently authorized REGEN-COV antibodies have diminished potency against Omicron but are active against the Delta variant.

REGEN-COV Availability

The U.S. HHS announced on September 13, 2021, that it is committed to ensuring consistent availability of critical drugs for current and future COVID-19 patients in all geographic areas of the U.S. On February 7, 2022, the U.S. HHS Assistant Secretary for Preparedness and Response confirmed (0) doses of REGEN-COV would be distributed in the U.S. Since October 2021, over 1.4 million doses of REGEN-COV were shipped in the U.S. This mAbs is not available for retail purchase as of March 2022.

The U.S. government established a call center dedicated to providing information on mAbs: 1-877-332-6585. And updated COVID-19 Monoclonal Antibody Therapeutics Frequently Asked Questions. U.S. facilities administering monoclonal antibodies can be found using the National Infusion Center Locator or the HHS Therapeutics Distribution locatorCMS billing information.

On November 12, 2021, European Commission approved REGEN-COV in the U.S. and Ronapreve™ in the European Union and the U.K.Switzerland, New Zealand, and Malaysia. The Company that applied for Ronapreve authorization was Roche Registration GmbH.


The concept that Monoclonal drug cocktails can prevent viral escape has been demonstrated for traditional antiviral drugs that treat HIV and other viruses. However, Regeneron now reports the fundamental realization that this can also be true for antibody-based therapies, as reported in a paper published in Science on August 21, 2020.

Regeneron scientists evaluated thousands of fully human antibodies produced by the Company's proprietary VelocImmune® mice, which have been genetically modified to have a human immune system and antibodies isolated from humans who have recovered from COVID-19. CDER Scientific Review Documents Supporting Emergency Use Authorizations for Drug and Biological Therapeutic Products for COVID-19 were updated by the U.S. FDA on September 9, 2021.

On September 23, 2021, the NEJM published an Original Article that concluded, 'Subcutaneous REGEN-COV prevented symptomatic Covid-19 and asymptomatic SARS-CoV-2 infection in previously uninfected household contacts of infected persons. In addition, among the participants who became infected, in a phase 3 study, REGEN-COV reduced the duration of symptomatic disease and the duration of a high viral load.'

The NEJM published results from a phase 3 study in an Original Article on September 30, 2021, that concluded by saying 'REGEN-COV reduced the risk of Covid-19–related hospitalization or death from any cause, and it resolved symptoms and reduced the SARS-CoV-2 viral load more rapidly than placebo.' In addition, a non-peer-reviewed retrospective analysis of immunodeficient patients published on November 9, 2021, found REGEN-COV treatment was associated with rapid viral clearance and clinical improvement in the evaluable patients with long-standing COVID-19.

On November 10, 2021, a non-peer-reviewed phase 3 study reported 'asymptomatic and low-risk symptomatic SARS-CoV-2-infected outpatients seronegative for antibodies against SARS-CoV-2 at baseline. REGEN-COV significantly and comparably reduced viral load at all IV and SC doses.' Additionally, another non-peer-reviewed clinical study published on November 14, 2021, found Repeat Subcutaneous Administration of REGEN-COV in Adults is Well-Tolerated and Prevents the Occurrence of COVID-19. In total, 969 subjects were treated. Repeat monthly dosing of 1200 mg SC REGEN-COV led to a 92.4% relative risk reduction in clinically-defined COVID-19.

REGEN-COV Indication

The REGEN-COV COVID-19 Monoclonal Antibody Cocktail Casirivimab and imdevimab (Ronapreve) are investigational therapies Authorized by the U.S. FDA for emergency use. REGEN-COV administered together are authorized for the treatment of mild to moderate COVID-19 in adults, as well as in pediatric patients at least 12 years of age and weighing at least 40 kg, who have received positive results of direct SARS-CoV-2 viral testing and are at high risk for progressing to severe COVID-19 and/or hospitalization.

The WHO suggests treatment with casirivimab-imdevimab, conditional to those at highest risk of hospitalization, and where viral genotyping can confirm a susceptible SARS-CoV-2 variant, excluding Omicron BA1.


Pregnancy: There are insufficient data to evaluate a drug-associated risk of significant congenital disabilities, miscarriage, or adverse maternal or fetal outcomes. REGEN-COV should only be used during pregnancy if the potential benefit outweighs the potential risk for the mother and the fetus REGEN-COV casirivimab and imdevimab injection therapy should be used during pregnancy only if the potential benefit justifies the mother and fetus's potential risk.

Nursing Mothers: There is no clinical experience using REGEN-COV (casirivimab and imdevimab) injection in COVID-19 patients breastfeeding. The development and health benefits of breastfeeding should be considered along with the mother's clinical need for casirivimab and imdevimab injection and any potential adverse effects on the breastfed child from injection or the underlying maternal condition.


In the U.S., REGEN-COV can be administered by intravenous infusion (as short as 20 minutes) or subcutaneous. The authorized dosage is 600 mg of casirivimab with 600 mg of imdevimab administered together as a single intravenous (IV) infusion or by subcutaneous injection as soon as possible after a positive viral test for SARS-CoV-2 and within ten days of symptom onset.

For individuals in whom repeat dosing is determined to be appropriate for ongoing exposure to SARS-CoV-2 for longer than four weeks and who are not expected to mount an adequate immune response to complete SARS-CoV-2 vaccination, the initial dose is 600 mg of casirivimab and 600 mg of imdevimab by subcutaneous injection or intravenous infusion followed by subsequent repeat dosing of 300 mg of casirivimab and 300 mg of imdevimab by subcutaneous injection or intravenous infusion once every four weeks for the duration of ongoing exposure.

A Phase 3 trial assessed the use of a single dose of investigational REGEN-COV (1,200 mg administered via four subcutaneous injections) to prevent COVID-19 in uninfected individuals found REGEN-COV reduced the risk of contracting COVID-19 (i.e., laboratory-confirmed symptomatic SARS-CoV-2 infections) by 81.6% during the pre-specified follow-up period (months 2-8), maintaining the 81.4% risk reduction during the first month after administration. Another phase 3 study supported by Regeneron Pharmaceuticals found a 1200 mg subcutaneous dose of REGEN-COV also prevented COVID-19 in household contacts of SARS-CoV-2-infected individuals.

REGEN-COV Children

The EMA's Committee for medicines issued its opinion on the Company's pediatric investigation plans for casirivimab and imdevimab on October 11, 2021, which describe how the medication should be developed and studied for use in children in accordance with the accelerated timelines for COVID-19 medicines. 

REGEN-COV Packaging

REGEN-COV is available in two distinct presentations: Dose pack bags: Dose pack bags will include a sufficient number of vials of casirivimab and imdevimab to prepare multiple doses. Co-formulated solution of REGEN-COV: The co-formulated solution of REGEN-COV contains two antibodies in a 1:1 ratio in a single dose vial consisting of 600 mg casirivimab and 600 mg of imdevimab per 10 mL (60 mg/60 mg per mL). Either presentation of REGEN-COV as described above may be prepared for intravenous infusion or subcutaneous injection.

The U.S. FDA published Temporary Alternative Packaging of Casirivimab and Imdevimab authorized to meet ongoing COVID-19 Public Health Demands on September 16, 2021. The Department of Health and Human Services Office of the Assistant Secretary for Preparedness and Response (ASPR) confirmed on October 8, 2021, that hospitals receiving this week's shipment of REGEN-COV should note that it will arrive in one of two packaging configurations: REGEN-COV Dose Packs (2 Vial) or Casirivimab and Imdevimab Co-Pack (2 vials per carton). ASPR says REGEN-COV in both packaging configurations may be used to prepare and administer intravenous infusions as well as subcutaneous injections. And a Quick Reference Guide was updated.

Medical information inquiries should be referred to Regeneron Medical Information at 1-844-734-6643.

REGEN-COV Side Effects

Clinical worsening of COVID-19 after administration of REGEN-COV has been reported. It may include signs or symptoms of fever, hypoxia or increased respiratory difficulty, arrhythmia (e.g., atrial fibrillation, tachycardia, bradycardia), fatigue, and altered mental status. The most common side effects were injection site reactions. The signs and symptoms of injection site reactions that occurred in at least 1% of subjects in the REGEN-COV group were skin redness (erythema), an uncomfortable, irritating sensation that creates an urge to scratch (pruritus), and ecchymosis (discoloration of the skin resulting from bleeding underneath, caused by bruising). There were no cases of severe hypersensitivity reactions, or potentially life-threatening allergic reactions (such as anaphylaxis), says the FDA.

People who had a previous severe allergic reaction to REGEN-COV should not use it again. Other important information for these trials, including different outcomes and side effects, is available in the health care provider fact sheet. In addition, on September 9, 2021, the EMA published COVID-19 treatment: Under Evaluation that is not explicitly authorized for patients with COVID-19.

Anyone can submit a report to VAERS, including parents and patients. And healthcare providers are required by law in the USA to report to VAERS.


In the U.S., the REGEN-COV2 Coding and Reimbursement Guide offers an overview of the relevant codes that may support reimbursement of the administration of REGEN-COV in outpatient settings. In September 2021, the US Department of Health and Human Services' 9th amended the Public Readiness and Emergency Preparedness Act declaration provide liability protection to licensed pharmacists, pharmacy technicians, and pharmacy interns to administer covered COVID 19 therapeutics. The U.S. CMS pays for mAbs infusions when furnished consistent with their respective EUAs. CMS identified specific code(s) for each COVID-19 monoclonal antibody product and specific administration codes (Q0240, Q0243, M0240, M0241) for payment.

Regeneron Inc. Financial News (NASDAQ REGN)

January 11, 2022 - Seeking Alpha reported U.S. net product sales of REGEN-COV (casirivimab and imdevimab) of ~$5.82B for FY 2021 and about $2.29B for Q42021.

November 4, 2021 - Regeneron Pharmaceuticals, Inc. posted better-than-expected third-quarter 2021 results, beating on earnings and sales, including $804 million attributable to REGEN-COV.

September 14, 2021 - Regeneron Pharmaceuticals, Inc. announced that the U.S. Department of Health and Human Services and the Department of Defense would purchase 1.4 million additional doses of REGEN-COV (casirivimab) imdevimab) 1,200 mg doses at the cost of $2,100 per dose. The U.S. government confirmed it would continue to provide REGEN-COV at no cost to patients. In September 2021, Regeneron expects to begin delivering the additional REGEN-COV doses to the U.S. government, with the vast majority delivered in Q4 2021.

August 5, 2021 - The Company announced Second quarter 2021 revenues increased 163% to $5.14 billion versus the second quarter of 2020, including $2.76 billion attributable to REGEN-COV; revenues excluding REGEN-COV(1)(2) increased 22%.

REGEN-COV News For 2022 - 2022

April 14, 2022 - Regeneron Pharmaceuticals, Inc. announced that the U.S. FDA had extended by three months its review of the Biologics License Application (BLA) for REGEN-COV to treat COVID-19 in non-hospitalized patients and as prophylaxis in certain individuals. The extension is due to ongoing discussions with the FDA on pre-exposure prophylactic use, for which Regeneron has submitted additional data from its completed prophylaxis trial that the FDA has accepted for review. The FDA considers the submission of these additional data to be a Major Amendment to the BLA and has provided a new target action date of July 13, 2022.

April 12, 2022 - The JAMA Network published an Original Investigation cohort study of 1959 propensity-matched outpatients with mild to moderate COVID-19 symptoms; the 28-day rate of hospitalization or death was 3.4% vs. 7.0% for those receiving subcutaneous treatment vs. nontreatment. In a second cohort analysis of 2185 outpatients, the 28-day rate of hospitalization or death was 2.8% vs. 1.7% for subcutaneous vs. intravenous treatment.

April 12, 2022 - Open Forum Infectious Disease published a study that concluded: Cas-Imd mAb treatment was associated with a lower hospitalization rate, ICU admission, and mortality within 30 days among patients infected with COVID-19 Delta variant.

March 14, 2022 - The EMA published updated clinical data regarding Ronapreve (Casirivimab / Imdevimab) EMEA/H/C/005814/0000.

March 3, 2022 - The WHO stated: With benefits of casirivimab-imdevimab observed only in patients with seronegative status, clinicians will need to identify these patients by credible tests available at the point of care to appropriately apply this recommendation. Treatment with casirivimab-imdevimab is in addition to the current standard of care, including corticosteroids and IL-6 receptor blockers.

February 7, 2022 - The European Medicines Agency website indicates Ronapreve remains authorized in the EU.

January 24, 2022 - The U.S. FDA confirmed the NIH COVID-19 Treatment Guidelines Panel, an independent panel of national experts, recently recommended against the use of REGEN-COV (casirivimab and imdevimab) because of markedly reduced activity against the omicron variant and because real-time testing to identify rare, non-omicron variants are not routinely available.  

January 20, 2022 - Miami, Florida-based media reported three additional mAbs treatment centers were recently opened.

January 19, 2022 - The U.S. NIH stated: Prior to mid-December 2021, the anti-SARS-CoV-2 mAbs casirivimab plus imdevimab was recommended by the Panel for nonhospitalized patients with mild to moderate COVID-19 who are at high risk of progressing to severe disease. The Omicron VOC, which has numerous mutations in the spike protein, is predicted to have markedly reduced susceptibility to casirivimab plus imdevimab. 

January 14, 2022 - The JAMA Network published an Original Investigation: Effect of Subcutaneous Casirivimab and Imdevimab Antibody Combination vs Placebo on Development of Symptomatic COVID-19 in Early Asymptomatic SARS-CoV-2 Infection. In this randomized phase 3 clinical trial that included 314 SARS-CoV-2 reverse transcriptase–quantitative polymerase chain reaction–positive individuals living with an infected household contact, 29% of asymptomatic seronegative participants treated with subcutaneous casirivimab and imdevimab, 1200 mg (600 mg of each antibody), developed symptomatic COVID-19 over 28 days vs 42.3% of those treated with placebo. This difference was statistically significant.

December 31, 2021 - In light of recent U.S. NIH clinical guidelines published on Dec. 30, 2021, and the significant variability in the prevalence of the Omicron Variant of Concern, all states and territories can continue to order REGEN-COV from HHS based on allocated amounts for clinically appropriate use.

December 16, 2021 - Regeneron issued a statement saying 'Regeneron has confirmed that multiple 'next generation' monoclonal antibodies from its large collection of fully human monoclonal antibodies targeting SARS-CoV-2 are active against the Omicron (B.1.1.529) and Delta (B.1.617.2) variants, as well as against the other variants of concern. Pending regulatory discussions, we anticipate entering the clinic in the first quarter of 2022.' However, currently authorized REGEN-COV antibodies to remain active against Delta, the most prevalent variant in the U.S.

December 14, 2021 - Malaysian Health director-general Tan Sri Dr. Noor Hisham Abdullah told local media Ronapreve has received conditional approval.

December 11, 2021 - The Minister of Health and Wellness of Mauritius confirmed around 500 doses of Ronapreve are expected to be delivered before the end of 2021.

December 7, 2021 - The Texas Department of State Health Services launched a new, no-cost, COVID-19 therapeutic infusion center in El Paso, Texas.

December 2, 2021 - The NEJM published an ORIGINAL ARTICLE: REGEN-COV Antibody Combination and Outcomes in Outpatients with Covid-19, a phase 3 study. CONCLUSIONS - REGEN-COV reduced the risk of Covid-19–related hospitalization or death from any cause, and it resolved symptoms and reduced the SARS-CoV-2 viral load more rapidly than placebo. 

November 30, 2021 - Regeneron confirmed it is evaluating REGEN-COV against the SARS-CoV-2 virus Omicron (B.1.1.529) variant. To date, there have been no direct data testing the Omicron variant's resistance to vaccine-induced and monoclonal antibody-conveyed immunity.

November 12, 2021 - The European Commission Approved REGEN-COV. Emergency or temporary pandemic use authorizations are currently in place in more than 40 countries, including the U.S., India, Switzerland, and Canada, and the antibody cocktail is fully approved in Japan and conditionally approved in the United Kingdom and Australia. 

November 8, 2021 - Regeneron Pharmaceuticals, Inc. announced additional positive results from a Phase 3 trial jointly run with the National Institute of Allergy and Infectious Diseases, which assessed the use of a single dose of investigational REGEN-COV (1,200 mg administered via four subcutaneous injections) to prevent COVID-19 in uninfected individuals. The new analyses show REGEN-COV reduced the risk of contracting COVID-19 (i.e., laboratory-confirmed symptomatic SARS-CoV-2 infections) by 81.6% during the pre-specified follow-up period (months 2-8), maintaining the 81.4% risk reduction during the first month after administration, which was previously reported in The NEJM in September 2021.

November 8, 2021 - Mary Talley Bowden, M.D., board-certified in Otolaryngology and Sleep Medicine, spoke with Precision Vaccinations, "I have treated 1,346 patients with REGEN-COV since August 2021. Our rate of subsequent hospitalization was 0.3%."

November 1, 2021 - The Journal of Internal Medicine published a Research Letter: Effectiveness of REGEN-COV antibody cocktail against the B.1.617.2 (delta) variant of SARS-CoV-2: A cohort study. In conclusion, REGEN-COV antibody cocktail-treated high-risk SARS-CoV-2 patients infected with the delta variant showed faster resolution of symptoms along with reduced viral loads.

October 14, 2021 - Regeneron Pharmaceuticals, Inc. announced that the U.S. Food and Drug Administration had accepted a Biologics License Application for REGEN-COV to treat COVID-19 in non-hospitalized patients for priority review as prophylaxis in certain individuals.

October 11, 2021 - The EMA announced it will assess the benefits and risks of Ronapreve under a reduced timeline and could issue an opinion within two months, depending on the robustness of the data submitted and whether further information is required to support the evaluation. Such a short timeframe is only possible because EMA's human medicines committee has already reviewed data on the medicine during a rolling review. 

October 11, 2021 - Chugai Pharmaceutical Co., Ltd. (TOKYO: 4519) announced an application with Japan's Ministry of Health, Labour, and Welfare for approval of additional indications for the anti-SARS-CoV-2 monoclonal antibody RONAPREVE for prophylaxis of COVID-19 and treatment of asymptomatic COVID-19 infected patients. This application also contains subcutaneous administration and the drug's current intravenous administration and seeks the Special Approval for Emergency.

October 8, 2021 - The South Carolina Department of Health and Environmental Control announced that it encourages healthcare facilities, providers, and eligible patients to take advantage of monoclonal antibody treatment.

October 7, 2021 - The COVID-19 Treatment Guidelines Panel recommended the use of anti-SARS-CoV-2 mAbs for the treatment of mild to moderate COVID-19 and for post-exposure prophylaxis of SARS-CoV-2 virus infection in individuals who are at high risk for progression to severe COVID-19, as outlined in the Food and Drug Administration EUAs issued for the anti-SARS-CoV-2 mAbs.

October 7, 2021 - Morehead, KY-based St. Claire HealthCare reported an alarming daily high of 49 hospitalized COVID-19 patients during September 2021, but that number has been cut in half today. According to Will Melahn, MD, SCH Chief Medical Officer, the availability of monoclonal antibody therapies like REGEN-COV is playing a significant role in lowering hospitalization rates.

October 6, 2021 - The journal NEJM published a CORRESPONDENCE: Subcutaneous REGEN-COV Antibody Combination to Prevent Covid-19. Providing only the relative risk measure may lead clinicians, patients, and laypeople to overestimate treatment efficacy.

October 2, 2021 - Local media reported Dr. William Agel, CMO for Cape Cod Hospital, and Cape Cod Healthcare had treated about 50 patients a week during a post-Labor Day surge. "It's been a great asset for the community."

September 29, 2021 - The NEJM published an ORIGINAL ARTICLE: REGEN-COV Antibody Combination and Outcomes in Outpatients with Covid-19. This phase 2/3 study found REGEN-COV reduced the risk of Covid-19–related hospitalization or death from any cause, and it resolved symptoms and reduced the SARS-CoV-2 viral load more rapidly than placebo.

September 30, 2021 - Texas Governor Greg Abbott today announced that the Texas Division of Emergency Management will open a new COVID-19 therapeutic infusion center in Burnet in partnership with local officials. Texas previously opened 23 centers and about 200 private health providers across the state.

September 30, 2021 - Regeneron Pharmaceuticals, Inc. announced a trial assessing investigational REGEN-COV™ (casirivimab and imdevimab) in 1,197 patients hospitalized with COVID-19 met its primary endpoint. Trial results show that REGEN-COV significantly reduced viral load in patients hospitalized with COVID-19. In addition, they entered the trial without having mounted their antibody response (seronegative) and required low-flow or no supplemental oxygen (p=0.0172). The trial also had clinical results supporting the much larger UK RECOVERY trial in hospitalized patients, with numeric improvements observed across all clinical endpoints assessed. In addition, Roche confirmed positive data from the phase II/III 2066 study investigating Ronapreve.

September 24, 2021 - The Regeneron antibody-drug cocktail REGEN-COV has been added to the World Health Organization's (WHO) list of treatments for COVID-19 patients.

September 23, 2021 - The NEJM published an ORIGINAL ARTICLE: Subcutaneous REGEN-COV Antibody Combination to Prevent Covid-19. In a phase 3 study, subcutaneous REGEN-COV prevented symptomatic Covid-19 and asymptomatic SARS-CoV-2 infection in previously uninfected household contacts of infected persons. In addition, REGEN-COV reduced the duration of symptomatic disease and a high viral load among the infected participants.

September 19, 2021 - Houston-based BreatheMD posted unverified, self-reported Monoclonal Antibody Treatment results on 410 Patients. About 97% of Regen-CoV patients would recommend the treatment to a loved one.

September 10, 2021 - Research presented found administration of Regeneron's REGEN-COV monoclonal antibody combination (casirivimab and imdevimab) reduced the risk of developing COVID-19 in participants with CVD and/or diabetes regardless of serostatus and was generally well tolerated. In addition, REGEN-COV treatment prevented symptomatic infection in participants with CVD (55% RRR) and/or diabetes (69% RRR), with effects independent of serostatus. "There is an unmet need for treatment options for individuals who are at an increased risk of moderate/severe COVID-19, including those with CVD and/or diabetes," the authors wrote.

August 30, 2021 - The Lancet published a research paper by EClinical Medicine: Casirivimab–Imdevimab treatment is associated with reduced hospitalization rates among high-risk patients with mild to moderate coronavirus disease-19. Interpretation - Among high-risk patients with mild to moderate COVID-19, casirivimab–imdevimab treatment was associated with a significantly lower hospitalization rate.

August 26, 2021 - Texas Governor Greg Abbott announced that the Texas Division of Emergency Management, in partnership with local officials, has expanded the number of locations where Regeneron's monoclonal antibodies are available to treat COVID-19 outpatient cases who have a referral from a doctor. This treatment is available at no cost to the patient. 

August 24, 2021 - Queen's North Hawai'i Community Hospital is expanding the use of Regeneron's REGEN-COV2. This intravenous treatment is provided on an outpatient basis to COVID patients. Initial doses have been successfully given in the QNHCH emergency room, and QNHCH has dedicated a clinic to this new treatment.

August 20, 2021 - Regeneron Pharmaceuticals, Inc. announced that the United Kingdom's Medicines and Healthcare products Regulatory Agency has granted Conditional Marketing Authorization for the casirivimab and imdevimab antibody cocktail, known as REGEN-COV™ in the U.S. and Ronapreve® in the U.K. and other countries, to prevent and treat acute COVID-19 infection. This announcement affects people in England, Scotland, Wales, and Northern Ireland. The MHRA has also authorized emergency supply of the antibody cocktail.

August 19, 2021 - Texas Governor Greg Abbott today announced that the Texas Department of State Health Services and the Texas Division of Emergency Management would deploy additional medical personnel and launch more COVID-19 antibody infusion centers across the state over the next week. These infusion centers, equipped with Regeneron's monoclonal antibodies, will treat COVID-19 patients at no cost with therapeutic drugs that can prevent their condition from worsening and requiring hospital care.

August 17, 2021 - Texas Governor Abbott confirmed receiving Regeneron's monoclonal antibody treatment. "Governor Abbott is fully vaccinated against COVID-19, in good health, and currently experiencing no symptoms."

August 12, 2021 - Florida Gov. Ron DeSantis announced Thursday that the state would dispense REGEN-COV2 monoclonal antibodies through mobile clinics. The governor championed Regeneron's monoclonal antibody cocktail for those who have already gotten sick, saying it is "the most effective treatment that we've yet encountered for people who are infected with covid-19." To find locations to receive monoclonal antibody treatments around the entire state, please visit

August 10, 2021 - The U.S. FDA authorized REGEN-COV2 monoclonal antibody therapy for post-exposure prophylaxis (prevention) for COVID-19.

August 5, 2021 - Regeneron Pharmaceuticals, Inc. announced financial results for the second quarter of 2021 and provided a business update. The Company fulfilled its second agreement with the U.S. government to manufacture and deliver 1.25 million doses of REGEN-COV at the lowest treatment dose authorized by the U.S. FDA and recognized $2.59 billion of REGEN-COV sales. In addition, in June 2021, the FDA updated the REGEN-COV EUA by lowering the dose to 1,200 mg and permitting administration by subcutaneous injection when the intravenous infusion is not feasible.

August 4, 2021 - The U.S. NIH added REGEN-COV2 as a recommended treatment for non-hospitalized patients with mild to moderate COVID-19 at high risk for clinical progression.

August 4, 2021 - Regeneron Pharmaceuticals, Inc. announced that the New England Journal of Medicine published detailed positive results from a Phase 3 trial that assessed the ability of REGEN-COV™ (casirivimab and imdevimab) to prevent COVID-19 infection among household contacts of SARS-CoV-2 infected individuals. The trial met its primary endpoint, reducing the risk of symptomatic infections by 81%, with a 93% reduction of symptomatic infections after the first week and no dose-limiting toxicities observed.

July 30, 2021 - Regeneron Pharmaceuticals, Inc. announced that the U.S. FDA updated the EUA for the investigational COVID-19 antibody cocktail REGEN-COV. The authorization now includes post-exposure prevention in people at high risk for progression to severe COVID-19, who are not fully vaccinated or are not expected to mount an adequate response to vaccination, and have been exposed to a SARS-CoV-2 infected individual, or who are at high risk of exposure to an infected individual because of infection occurring in the same institutional setting (such nursing homes or prisons).

July 20, 2021 - Japan Approved Regeneron's casirivimab and imdevimab antibody cocktail (Ronapreve) to treat patients with mild to moderate COVID-19. This Approval is the first time the antibody cocktail has received full Approval to treat COVID-19. 

June 16, 2021 - Regeneron Pharmaceuticals, Inc. confirmed positive results from the most significant trial assessing any monoclonal antibody treatment in patients hospitalized with severe COVID-19. The UK RECOVERY trial found that adding investigational REGEN-COV™ to usual care reduced the risk of death by 20% in patients who had not mounted a natural antibody response on their own against SARS-CoV-2, compared to standard care on its own.

June 9, 2021 - Canada Health Authorized By Interim Order (249830) Casirivimab and imdevimab for use concerning the COVID-19 pandemic, per section 5 of the Interim Order Respecting the Importation, Sale, and Advertising of Drugs for Use concerning COVID-19.

June 4, 2021 - Regeneron Pharmaceuticals, Inc. announced the U.S. Food and Drug Administration (FDA) updated the Emergency Use Authorization (EUA) for REGEN-COV™, lowering the dose to 1,200 mg (600 mg casirivimab and 600 mg imdevimab), which is half the dose initially authorized. As part of the updated EUA, REGEN-COV should be administered by intravenous infusion; subcutaneous injections are an alternative when IV infusion is not feasible and would delay treatment. REGEN-COV has not been approved by FDA but has been Authorized for emergency use.

June 4, 2021 - The U.S. government will purchase all REGEN-COV doses delivered by June 30, 2021, and may accept additional doses through September 30, 2021, at its discretion, up to a maximum amount of 1.25 million doses. Regeneron expects to deliver at least 1 million REGEN-COV doses to the U.S. government in the 2Q'21.

June 3, 2021 - The U.S. FDA issued a letter that stated: 'having concluded that revising this EUA is appropriate to protect the public health or safety under section 564(g)(2) of the Act, FDA is reissuing the February 25, 2021 letter in its entirety, authorizing revisions to the authorized use6 for REGEN-COV, a change in dosing of REGEN-COV from 2400 mg (1200 mg casirivimab and 1200 mg imdevimab) to 1200 mg (600 mg casirivimab and 600 mg imdevimab), and the addition of a new presentation consisting of a single vial containing casirivimab and imdevimab co-formulated in a 1:1 ratio for either intravenous infusion or subcutaneous injection. New conditions have been incorporated on providing samples of the authorized REGEN-COV to the U.S. Department of Health and Human Services upon request and the submission of certain genomic sequencing and virology information to the FDA by a specified date.'

April 9, 2021 - Regeneron Pharmaceuticals, Inc. announced that the newly updated National Institutes of Health (NIH) COVID-19 Treatment Guidelines strongly recommend that REGEN-COV™ (casirivimab with imdevimab) be used in non-hospitalized COVID-19 patients ("outpatients") at high risk of clinical progression.

March 23, 2021 - Regeneron announced their antibody cocktail's phase 2 and 3 results. REGEN-COV in high-risk non-hospitalized COVID-19 patients met its primary endpoint, showing the investigational REGEN-COV (casirivimab with imdevimab) significantly reduced the risk of hospitalization or death by 70% compared to placebo. Additionally, REGEN-COV significantly shortened the duration of symptoms by four days. The phase 2 dose-ranging showed significant and comparable viral reductions for all REGEN-COV doses tested, including as low as 300 mg.

February 4, 2021 - The European Medicine Agency (EMA) announced the human medicines committee is reviewing available data on the use of the monoclonal antibodies casirivimab, imdevimab, bamlanivimab, and etesevimab to treat patients with COVID-19 who do not require oxygen supplementation and who are at high risk of progressing to severe COVID-19.

February 1, 2021 - The European Medicines Agency (EMA) announced the human medicines committee (CHMP) had started a 'rolling review' of data of the medicine known as REGN-COV2 antibody combination (casirivimab / imdevimab), which is being co-developed by Regeneron Pharmaceuticals, Inc. and F. Hoffman-La Roche, Ltd (Roche) for the treatment and prevention of COVID-19.

January 26, 2021 - Regeneron Pharmaceuticals, Inc. announced positive initial results from an ongoing Phase 3 clinical trial evaluating REGEN-COV™ (casirivimab and imdevimab antibody cocktail) used as a passive vaccine for the prevention of COVID-19 in people at high risk of infection (due to household exposure to a COVID-19 patient). Passive vaccination with REGEN-COV resulted in 100% prevention of symptomatic infection (8/223 placebo vs. 0/186 REGEN-COV) and approximately 50% lower overall rates of infection (symptomatic and asymptomatic) (23/223 placebo vs. 10/186 REGEN-COV).

January 21, 2021 - The NEJM published an ORIGINAL ARTICLE - REGN-COV2, a Neutralizing Antibody Cocktail, in Outpatients with Covid-19. In this interim analysis, the REGN-COV2 antibody cocktail reduced viral load, with a more significant effect in patients whose immune response had not yet been initiated or who had a high viral load at baseline.

December 17, 2020 - The NEJM published a study that found 'In this interim analysis, the REGN-COV2 antibody cocktail reduced viral load, with a greater effect in patients whose immune response had not yet been initiated or who had a high viral load at baseline. In addition, safety outcomes were similar in the combined REGN-COV2 dose groups and the placebo group.'

November 21, 2020 - The U.S. Food and Drug Administration issued an emergency use authorization (EUA) for casirivimab and imdevimab to be administered together for the treatment of mild to moderate COVID-19 in adults and pediatric patients (12 years of age or older weighing at least 40 kilograms with positive results of direct SARS-CoV-2 viral testing and who are at high risk for progressing to severe COVID-19. This includes 65 years of age or older or certain chronic medical conditions.

June 11, 2020 - Regeneron announced the first clinical trial of REGN-COV2, an investigational antibody cocktail to prevent and treat COVID-19.

REGEN-COV2 (Ronapreve) Monoclonal Antibody Cocktail (Casirivimab and Imdevimab) Clinical Trials

REGEN-COV continues to be studied in various clinical trials to assess safety, Tolerance, Pharmacokinetics, and Immunogenicity against COVID-19.

Phase 3 study - NCT04452318 - Randomized, Double-Blind, Placebo-Controlled Study Assessing the Efficacy and Safety of Anti-Spike SARS-CoV-2 Monoclonal Antibodies in Preventing SARS-CoV-2 Infection in Household Contacts of Individuals Infected With SARS-CoV-2 - published results in the NEJM on September 23, 2021. And on January 14, 2022, the JAMA Network - Conclusions and Relevance:  Among asymptomatic SARS-CoV-2 RT-qPCR–positive individuals living with an infected household contact, treatment with subcutaneous casirivimab and imdevimab antibody combination vs placebo significantly reduced the incidence of symptomatic COVID-19 over 28 days.

Clinical Trials