Treating COVID-19: What are monoclonal antibodies?


The use of monoclonal antibodies in healthcare isn’t new. In fact, doctors have been using them for decades in the treatment of certain illnesses, such as cancer.

Now, they’re being used to treat people infected with COVID-19 who are at a high risk of severe illness — and early results are promising.


Our immune systems naturally create millions of proteins, called antibodies. These antibodies search for and attach themselves to foreign cells (or antigens) and help the immune system fight off harmful antigens, like viruses.

Monoclonal antibodies are laboratory-made proteins that mimic our immune system’s ability to fight off antigens, like the SARS-CoV-2 virus that causes COVID-19.

These one-time antibody treatments are being administered via intravenous infusion to help treat COVID-19.

What makes monoclonal antibodies unique is that they’re one of the few new treatment options available for people before they’re sick enough to require hospitalization.


Like other treatments or emergency therapies that have been used during the coronavirus pandemic, monoclonal antibodies have received emergency use authorization from the U.S. Food and Drug Administration.

This means that while the treatment is still considered experimental, it’s been made available in a limited capacity while research continues.

Currently, monoclonal antibody treatments from pharmaceutical companies Regeneron and Eli Lilly are approved for use. And both have reported promising results.

The results of Eli Lilly’s final-stage trial showed that their treatment was effective in those with a high risk of severe illness from COVID-19, reducing the risk of hospitalization.

Regeneron and Eli Lilly have both reported that their antibody treatments help prevent hospitalizations from COVID-19.

So far, we’re seeing that monoclonal antibodies can help limit the number of people who require hospitalization. And that relieves strain on hospitals and healthcare workers.

Preliminary research also suggests that monoclonal antibodies appear to be effective against COVID-19 variants, too.


Who can get the monoclonal antibody treatment?

Supplies are limited right now, so monoclonal antibodies are being administered to those who have the greatest chance of benefiting from the treatment.

This treatment is being used for non-hospitalized patients in the early stages of COVID-19 infection. And there’s specific criteria to be eligible for treatment.

These criteria include being 65 and older and/or being at high risk of severe illness (e.g., having a chronic medical condition like diabetes, chronic kidney disease or COPD). The treatment must also be administered within 10 days of a COVID-19 diagnosis and are only for those with moderate to severe symptoms.

At Geisinger, we’re evaluating patients who test positive for COVID-19 to see if they are eligible to receive monoclonal antibodies and contacting them based on the amount of supply we have. Doctors may also refer patients for treatment if they test positive for COVID-19 outside of Geisinger and meet the criteria as defined by the emergency use authorization.


With any experimental treatment or therapy, it’s understandable to be concerned about potential side effects. During clinical trials of monoclonal antibodies, few side effects were reported.

The most common side effects were nausea, diarrhea, dizziness, headache, skin irritation and vomiting.


While monoclonal antibodies are a potential tool to prevent COVID-19 hospitalizations and reduce the strain on healthcare organizations, supplies are extremely limited right now.

It’s important that everyone continue to take precautions, like masking, physical distancing and handwashing, to help slow the spread of COVID-19. We’re looking forward to when monoclonal antibody treatments are more readily available so they can be offered to everyone who can benefit from them.

Dr. Keith Boell is Geisinger’s chief quality officer for population initiatives.


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