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What Are Monoclonal Antibodies? How Are They Used to Treat COVID-19?

Updated Aug. 11, 2021

Scientists have been working hard to find new ways to treat COVID-19. Monoclonal antibodies are one of the most promising treatments.

To learn more about Monoclonal Antibody Treatment for COVID-19, and to see if you qualify, please call 866-804-5251.

The U.S. Food and Drug Administration (FDA) has authorized multiple monoclonal antibody treatments for COVID-19. Here’s what you need to know.

What Are Monoclonal Antibodies?

When a pathogen such as a virus or bacteria enters the body, your immune system recognizes it as foreign.

Your immune system then produces Y-shaped proteins called antibodies that attach to the pathogen and stop it from entering cells. Antibodies also help destroy the pathogen.

Monoclonal antibodies are antibodies that scientists have created in the lab to act like “substitute” antibodies in someone with a disease.

Researchers design monoclonal antibodies to attach to a single specific substance in the body. These antibodies help the immune system attack the disease by mimicking the body’s antibodies or supporting the immune system’s work.

“We’ve designed the monoclonal antibodies to block the ability of the virus to attach and enter into your cells,” says Graham Snyder, MD, medical director, Infection Prevention and Hospital Epidemiology, UPMC. “Essentially, it’s now floating around helpless and weak, so your body can clear it out.”

Several different monoclonal antibodies are already important in fighting certain cancers or slowing the progression of diseases such as rheumatoid arthritis.

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How Do Monoclonal Antibodies Fight COVID-19?

The FDA has issued emergency use authorization (EUA) for multiple different monoclonal antibodies to treat COVID-19:

  • A combination of the drugs casirivimab and imdevimab given together (REGEN-COV).
  • An antibody given alone, sotrovimab .

These drugs specifically look for and attach to the spike protein that sticks out of the coronavirus that causes COVID-19. When they attach to the spike protein, they can block the virus’s ability to enter cells. This slows down infection and allows your body to fight off the disease.

More potential monoclonal antibody treatments could become available in the future.

Who Is Eligible for Monoclonal Antibodies for COVID-19?

Currently, the FDA has authorized monoclonal antibodies for outpatients who have mild or moderate COVID-19 with a high risk of progressing to severe disease.

This group includes older adults and those who have chronic medical conditions. Mild to moderate COVID-19 can become a severe case, so the goal is to treat it before that happens.

On May 24, 2021, the FDA expanded its eligibility criteria to include more groups of people who can now receive the treatment.

“We are delighted to know that they have broadened the criteria so that virtually all can receive this potentially lifesaving treatment,” says Tami Minnier, MSN, RN, chief quality officer, UPMC.

People who are eligible for monoclonal antibodies include the following:

  • People 65 and older.
  • People with a body mass index (BMI) over 25.
    • Children between the ages of 12 and 17 are eligible if their BMI is in the 85th percentile for their age and sex, based on CDC growth charts.
  • Pregnant women.
  • People with medical conditions, including:
    • Cardiovascular disease (including congenital heart disease and hypertension).
    • Chronic kidney disease.
    • Chronic lung disease (i.e. COPD).
    • Dementia.
    • Diabetes.
    • Down syndrome.
    • Immunosuppressive disease, including cancer, or an immunosuppressive treatment.
    • Liver disease.
    • Neurodevelopmental disorders or other conditions that confer medical complexity.
    • Sickle cell disease.
    • Stroke or cerebrovascular disease.
  • People with a current or former history of smoking or substance abuse.
  • People who have a medical-related technological dependence (i.e. tracheostomy, gastrostomy).

Patients must be at least 12 years old and weigh at least 88 pounds to receive monoclonal antibody treatments.

The treatment must be given within 10 days of a positive COVID-19 test or the start of symptoms. You also can receive the treatment even if you’ve gotten the COVID-19 vaccine.

“The most important thing is if you are diagnosed with COVID-19, even if your symptoms are mild, even if you’ve been vaccinated, ask about monoclonal antibodies,” Minnier says. “There’s a good chance you’re eligible, and they work best the sooner we can get them to you.”

The FDA has not yet authorized monoclonal antibodies for people who already have severe COVID-19, including people who are hospitalized or receiving oxygen treatment. Dr. Snyder says more data is needed before the FDA can authorize monoclonal antibodies for severe COVID-19.

Monoclonal antibodies as preventive treatment

In July 2021, the FDA expanded the EUA for the REGEN-COV antibody treatment. People can now receive REGEN-COV as a preventive treatment after getting exposed to SARS-CoV-2 but before testing positive for COVID-19.

To be eligible for the preventive treatment, you must:

  • Be at least 12 years old and weigh at least 88 pounds.
  • Be exposed as a close contact to someone infected with COVID-19.
  • Be at high risk for severe illness from COVID-19.
  • Be unvaccinated or not fully vaccinated, OR someone who is fully vaccinated but who is not expected to have an adequate immune response to the vaccine (i.e. immunocompromised).

How Do Monoclonal Antibody Treatments Work?

Patients receive monoclonal antibody treatments as intravenous (IV) infusions. An infusion involves placing a needle in a vein and gradually sending the medicine through the IV.

Patients must receive this treatment at an office or clinic that’s able to provide infusions. A medical professional administers the treatment and monitors the patient for any serious reactions.

The treatments involve a one-time IV infusion that takes about one hour. Patients also must wait at least one hour after the infusion ends so clinicians can watch for any negative reactions.

How Effective Are Monoclonal Antibodies?

Scientists tested the monoclonal antibody treatments in clinical trials. The treatments reduced hospitalizations and emergency room visits for people with COVID-19 during the 28 days after receiving the monoclonal antibodies.

A May 2021 study from UPMC and the University of Pittsburgh School of Medicine reported monoclonal antibodies cut the risk of hospitalization and death in our patients by 60% when given shortly after COVID-19 infection.

“It’s incredibly effective in bending the disease outcome,” says Donald Yealy, MD, senior vice president and chief medical officer, UPMC.

“In other words, you’re much less likely to need hospital care or to have a serious or bad outcome after getting monoclonal antibody therapy, if you get it early. So if you get sick, or if you come to know of a positive test, ask early about it. Don’t wait. It works better before the disease is entrenched.”

The FDA and researchers are continuing to study monoclonal antibodies to see how well they treat and prevent COVID-19.

Are Monoclonal Antibodies Safe?

According to reported data, monoclonal antibodies are safe. The most common side effects are infusion site reactions and allergic reactions. Those could include pain, bleeding, skin bruising, soreness, swelling, and infection at the infusion site.

Other potential side effects could include:

  • Difficulty breathing
  • Fever
  • Nausea/vomiting
  • Rapid/slow heart rate
  • Tiredness
  • Weakness
  • Confusion
  • Hyperglycemia
  • Pneumonia

Serious side effects are rare. Talk to your doctor if you experience any side effect that doesn’t go away within a few days.

Does UPMC Offer Monoclonal Antibodies?


 monoclonal antibodies

UPMC is currently providing monoclonal antibodies to patients with mild or moderate COVID-19 who are at risk of severe illness. To date, UPMC has provided thousands of monoclonal antibody treatments across the communities we serve.

We are providing the treatment at dozens of UPMC facilities, including infusion centers and Emergency Departments. We also can bring the treatment to patients in their homes, in long-term care facilities, and in behavioral health centers.

UPMC is committed to providing equal access to monoclonal antibodies to communities of color and other communities severely affected by COVID-19.

“This disease has disproportionately affected communities of color,” says Steven Evans, MD, surgical oncologist, UPMC Hillman Cancer Center. “We at UPMC have taken every precaution to mitigate any racial disparity in our administration of this lifesaving treatment. Black, Brown, and white all are receiving this treatment at equal rates.”

To learn more about monoclonal antibodies, or to schedule an infusion appointment:


National Cancer Institute. Monoclonal antibody. Link

US Food and Drug Administration. Coronavirus (COVID-19) Update: FDA Authorizes Monoclonal Antibody for Treatment of COVID-19. November 9, 2020. Link

US Food and Drug Administration. Coronavirus (COVID-19) Update: FDA Authorizes Monoclonal Antibodies for Treatment of COVID-19. November 21, 2020. Link

US Food and Drug Administration. COVID-19 Frequently Asked Questions. Link

US Food and Drug Administration. Fact sheet for healthcare providers emergency use authorization (EUA) of bamlanivimab. Link

US Food and Drug Administration. Fact sheet for healthcare providers emergency use authorization (EUA) of casirivimab and imdevimab. Link

About UPMC

Headquartered in Pittsburgh, UPMC is a world-renowned health care provider and insurer. We operate 40 hospitals and 700 doctors’ offices and outpatient centers, with locations in central and western Pennsylvania, Maryland, New York, and internationally. We employ 4,900 physicians, and we are leaders in clinical care, groundbreaking research, and treatment breakthroughs. U.S. News & World Report consistently ranks UPMC Presbyterian Shadyside as one of the nation’s best hospitals in many specialties and ranks UPMC Children’s Hospital of Pittsburgh on its Honor Roll of America’s Best Children’s Hospitals.