What to Know About Monoclonal Antibodies

The FDA pulls back another treatment that doesn't work against omicron, and the federal government warns that without more funding it'll run out of antibodies to give states.

Jessica Rendall Wellness Writer
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A monoclonal antibody treatment made by GlaxoSmithKline and Vir is no longer authorized to treat COVID-19 in the US because it doesn't work against omicron's subvariant, BA.2, the US Food and Drug Administration said Tuesday

Ba.2 or "stealth omicron" is now responsible for more than 70% of COVID-19 cases in the United States, data from the US Centers for Disease Control and Prevention shows, meaning most people who get sick with COVID-19 now will have the newer form of omicron. In March, GlaxoSmithKline said the FDA found that its treatment sotrovimab "unlikely" to be effective against the BA.2 variant. The companies added that they are preparing data on a higher dose of sotrovimab that may work against BA.2.

Sotrovimab, like other monoclonal antibodies, has been used as treatment for COVID-19 in people most at risk for severe COVID-19 disease or hospitalization in the early days of their symptoms.

Bebtelovimab, made by Eli Lilly, is a monoclonal antibody still authorized for use in patients 12 and up who have mild or moderate COVID-19 and are at high risk for severe disease. The antibody should be used when other treatments for high-risk patients are either unavailable or inappropriate, and given within the first seven days of COVID-19 symptoms, the FDA said. 

In January, the FDA pulled back emergency use authorization of an earlier monoclonal antibody treatment made by Eli Lilly and also one from Regeneron (REGEN-COV) because they no longer worked to prevent severe disease caused by the omicron variant. But in the future, the FDA noted, these treatments may be used when it's likely someone was infected with or exposed to a variant the drugs are effective against.

Other treatments still available for at-risk patients include Paxlovid, molnupiravir and remdesivir. In January, the FDA expanded use of remdesivir for treating at-risk patients in the early days of their illness, including in children under 12. Previously, it was authorized only for people hospitalized with COVID-19. 

In March, the White House warned that without more COVID-19 funding from Congress, the US will run low on the testing, treatment and vaccine supplies it's depended on in its pandemic response. Though a smaller pandemic package is now being debated in the Senate, without action the federal supply of monoclonal antibodies shipped to states will run out as soon as late May, according to the Biden administration.

Here's what to know about monoclonal antibodies.

Read more: Free COVID Antiviral Pills: New Official Website Helps Find Them


A monoclonal antibody treatment center in Pembroke Pines, Florida. 

Chandan Khanna/Getty

What are monoclonal antibodies, and how do they work? 

Monoclonal antibodies are lab-made antibodies that work by binding to bacteria, cancer cells or viruses the way natural antibodies do, stopping them from infecting more cells. The first monoclonal antibody therapy was approved more than 30 years ago and has been used for other diseases, including cancer

Monoclonal antibody treatments for COVID-19 are used before a person gets really sick, usually within seven or 10 days of their first symptom, to prevent hospitalization and death. The antibodies aren't used in someone who is already hospitalized and being treated with supplemental oxygen, for example. 

One monoclonal antibody therapy made by AstraZeneca (Evusheld) is authorized for preventive use, before a person is sick or exposed, but only for people who are immunocompromised or those who don't mount an adequate immune response to the COVID-19 vaccines. 

Who's eligible?

Monoclonal antibody treatments, as well as other COVID-19 treatments, are reserved for people most at risk for severe COVID-19 disease, which includes adults age 65 and up and people living with medical conditions such as diabetes, asthma, obesity and more. Monoclonal antibody treatment is typically given through an IV or infusion.

Eli Lily's authorized bebtelovimab antibody is for high-risk patients 12 and older with mild or moderate disease, but treatment must be given within seven days of the first symptom. If people have a positive COVID-19 test but didn't develop symptoms, they don't meet the criteria of "mild or moderate" disease, according to a fact sheet. It'll also be administered if other treatments are either inaccessible or inappropriate for the patient, the FDA said. The New York Times reported this is likely because though data shows the antibody is effective against omicron, the drug hasn't been tested in a study that definitively shows it prevents severe disease.

Why did the FDA stop the use of some monoclonal antibodies?

The virus that causes COVID-19 has mutated over time and has reduced the effectiveness of some COVID-19 treatments, including the monoclonal antibodies. This is because the antibody treatments are lab-made proteins that mimic the immune system's ability to fight off viruses, according to the FDA, which need to be a good enough match for the current variant or subvariant.

How do I get treatment? Is it free?

The government has agreed to purchase COVID-19 treatments as part of its pandemic response, including doses of monoclonal antibodies. This means the drug itself is free, and the administration fee may be waived as well, depending on your insurance. 

Americans without health insurance, however, may be on the hook for an administration fee (what it costs for someone to actually give you the treatment) as the Uninsured Program stopped accepting claims from providers treating, testing or vaccinating Americans without health insurance, citing a "lack of sufficient funds."

If you don't have health insurance and you're seeking monoclonal antibody treatment or another therapy, call the clinic you plan to visit to see if, or how much, you'll have to pay. It may depend on the clinic and on state and other resources available at a local level.

The same funding problem affecting people without health insurance is also on track to disrupt the nation's supply of monoclonal antibodies. Doses may run out as soon as late May, the White House said, but a bill currently being argued over in the Senate would replenish some of the country's pandemic needs. It might also reinstate options available to people without health insurance. 

To find treatment near you, you can call the Combat COVID Monoclonal Antibodies Call Center at 1-877-332-6585 or your primary care doctor.

Do monoclonal antibodies interfere with the coronavirus vaccines? 

If you were treated with monoclonal antibodies and you haven't been vaccinated yet, you should wait 90 days after your treatment to get the shot, according to the CDC. This recommendation is until more is known about how the antibody response from the treatment affects the immune response from getting vaccinated.

Everyone age 5 and up is eligible for a COVID-19 vaccine in the US.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.