The onslaught of the SARS-CoV-2 (COVID-19) pandemic has presented an “unprecedented challenge to develop and identify effective medication strategies.”1 Among several agents under investigation, monoclonal antibodies have emerged as key “promising” interventions for disease management.2 Given that many of these new agents are still under development, the US Food and Drug Administration (FDA) has issued several emergency use authorizations (EUAs) to make these agents available on an emergent basis to affected patients.

At present, 3 monoclonal antibody therapies have EUA status: the combination of bamlanivimab and etesevimab (Eli Lilly), the combination of casirivimab and imdevimab (also called REG-COV, Regeneron), and sotrovimab (GlaxoSmithKline and Vir Biotechnology). Other agents are under development but have not yet received EUA.

To shed light on antibody therapy for COVID-19, we spoke to Jason C. Gallagher, PharmD, Clinical Professor and Clinical Specialist at Temple University in Philadelphia. Dr Gallagher is also the Infectious Diseases Director, PGY2 Residency in Infectious Diseases Pharmacy at Temple University and a coauthor of the updated Infectious Disease Society of America’s Guideline on the Treatment and Management of COVID-19.3

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What is the mechanism of action of monoclonal antibodies for COVD-19?

Most monoclonal antibodies under development for COVID-19 target the spike glycoprotein, which is what the virus uses to enter host cells.4 When the spike protein is blocked, the result is that viral attachment and entry into our cells is blocked. Putting it another way, monoclonal antibodies take the normal response that the immune system would generate over time and, when administered early in the course of the infection, they “jump start” this process and accelerate it so the antibodies can go to work sooner than we can develop them. For this reason, antibody therapy should be initiated as soon as possible after a positive diagnosis, preferably within 10 days.5

Who should receive antibody therapy?

The IDSA recommends that antibody therapy should be administered to patients with mild to moderate COVID-19 at high risk for progression to severe disease.

What are the advantages of having multiple available antibody regimens, rather than just one?

An increasing concern in treating COVID-19 is the presence of a range of variants that might be resistant to treatment. Some of these variants have reduced susceptibility to the currently available antibodies, while others are more responsive, so it is helpful to have multiple antibody treatment options available for use, based on variants in a given geographical area.

More information is available on the monoclonal antibody EUA fact sheets. It encourages use of antibody treatments, with a particular focus on treatment selection based on local variants.

Monoclonal antibodies for COVID-19 are authorized for children as young as 12 years old. Do you have any concerns or suggestions that are specific to this age group?

Since children in general are at much lower risk for severe COVID-19, there are fewer kids overall who are at high enough risk of severe disease to justify using monoclonal antibodies. Those children who meet these limited criteria should receive antibody therapy as soon as possible after diagnosis, and I would not hesitate merely because of the age. This is the only means we have to prevent a patient from needing hospitalization. The treatment is generally well tolerated, and I am not aware of any known side effects that would be specific to pediatric patients, as opposed to patients of other ages.

Are there any absolute contraindications to use of monoclonal antibodies in particular types of patients with COVID-19?

The only absolute contraindication is hypersensitivity, which would imply that someone has received the antibody therapy before. That is a very rare situation.

Can a person who has received antibody treatment get vaccinated against COVID-19?

According to the CDC,6 there are currently no data on the safety or efficacy of COVID-19 vaccines in people who have been treated with monoclonal antibodies. However, given evidence suggesting that reinfection is uncommon during the 90 days following an initial infection, the CDC recommends that vaccination should be deferred for at least 90 days following antibody treatment. The CDC regards this as a “precautionary measure” to avoid potential interference of the antibody therapy with vaccine-induced immune responses.

Do you think monoclonal antibody therapy is sufficiently prescribed for patients with COVID-19?

In my experience, antibody therapy for COVID-19 is underprescribed. One reason is lack of knowledge about this type of treatment approach. Hopefully that is changing as guidelines such as that of the IDSA recommend it, and as it becomes increasingly established.

Another reason for this underprescription is lack of awareness on the part of some practitioners about where to refer patients. Prescribers should be aware that the US Department of Health and Human Services offers a Web tool specifically dedicated to locating facilities that provide COVID-19 antibody treatment. The National Infusion Center Association similarly offers an infusion locator tool.

Encouragingly, availability of antibody treatment is expanding. At the end of March, the Biden administration pledged $150 million to expand access to antibody treatments, especially in underserved areas.7 This should go a long way toward making antibody treatment available in areas where it was not previously.

Is monoclonal antibody therapy costly for the patient?

Many clinicians are not aware that patients can receive antibody therapy at no cost to them. Medicare and Medicaid cover the treatment, as do most other insurance companies, under the FDA’s EUA.

What concerns do patients bring up and how might they be addressed?

Many patients find the infusion process onerous as well, since they must be in a location where there is immediate access to medications to treat a severe infusion reaction (eg, anaphylaxis) and must be under observation for an hour following the infusion to monitor for adverse effects.

Nevertheless, these agents have shown a high level of efficacy in treating COVID-19 and these practical concerns should not deter clinicians from referring patients for treatment.

I encourage clinicians to provide patients with reliable resources for education about antibody therapy (Table 1). There are many misconceptions in this day and age about all aspects of COVID-19 that accurate information is essential and will also encourage eligible patients to be treated with antibody therapy.

Table 1

Patient Education Websites

National Infusion Center Association

US Department of Health and Human Services


  1. Yang X, Liu Y, Liu Y, Yang Q, Wu X, Huang X, Liu H, Cai W, Ma G. Medication therapy strategies for the coronavirus disease 2019 (COVID-19): recent progress and challenges. Expert Rev Clin Pharmacol. Published online August 4, 2020.
  2. US Department of Health and Human Services. Monoclonal antibodies for high-risk COVID-19 patients. Available at: Accessed: April 13, 2021.
  3. Bhimraj A, Morgan RL, Shumaker AH, Lavergne V, Baden L, Chi-Chung Cheng V, et al. IDSA Guidelines on the Treatment and Management of Patients with COVID-19. April 14, 2021. Available at: Accessed: April 20, 2021.
  4. Infectious Disease Society of America. Monoclonal Antibodies. Available at: Accessed: April 30, 2021.
  5. National Institutes of Health (NIH). Anti-SARS-CoV-2 Monoclonal Antibodies. Available at: Accessed: April 21, 2021.
  6. Centers for Disease Control and Prevention (CDC). Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Authorized in the United States. Paged reviewed May 14, 2021. Available at: Accessed: May 16, 2021.
  7. US Department of Health and Human Services. Biden Administration to Invest $150 Million to Expand Access to COVID-19 Treatments in Underserved Communities March 17, 2021. Available at: Accessed: April 18, 2021.

This article originally appeared on MPR