---
title: H5N1 bird flu and the promise of monoclonal antibodies
description: A monoclonal antibody could offer a defence against the H5N1 avian flu. Researchers are focussing on new targeted therapies.
---

[Blog | IBSA Foundation ](https://www.ibsafoundation.org/en/blog)

# [H5N1 bird flu and the promise of monoclonal antibodies](https://www.ibsafoundation.org/en/blog/monoclonal-antibody-against-avian-flu-h5n1)

 Written by [Paolo Rossi Castelli](https://www.ibsafoundation.org/en/blog/author/paolo-rossi-castelli) | 21 Feb 2025

A monoclonal antibody developed in the United States could provide new protection against H5N1 bird flu. Tests in non-human primates confirm its efficacy against more severe disease. The researchers are zeroing in on new targeted therapies, applying the knowledge gained during the Covid-19 pandemic.

There is growing alarm across Europe, after the United States, about the spread of **H5N1 bird flu**, which is affecting masses of farmed and wild birds, but also mammals. In recent months it has also begun to infect **humans**, albeit in small numbers and primarily people who were in close contact with infected animals, leading to **death** in some cases.

 

### **The monoclonal antibody MEDI8852: a possible solution to H5N1 bird flu**

But hope is now on the horizon, with regard to the possibility of creating **drugs capable of curbing the most severe situations**. A new study published in the [journal ***Science***](https://www.science.org/doi/10.1126/science.ado6481) shows the potential of a **broadly neutralising monoclonal antibody** (**bnAb**) called **MEDI8852. **

This bnAb has proven very effective in tests on **non-human primates**. And while it can’t prevent infection (which is instead the job of vaccines), it does seem able to **protect against the development of more dangerous bird flu**. If necessary, this antibody can be tested and used on humans too, say the researchers.

### **How does the monoclonal antibody work against the H5N1 virus?**

Researchers at the **University of Pittsburgh** and the US **National Institutes of Health** **Vaccine Research Center** used the same approach as the one explored during the **Covid-19 pandemic** to find **more effective therapies** when it had become clear that the **coronavirus was mutating rapidly**. The **H5N1 virus** also undergoes **constant** mutation, which is why the scientists decided to **search its genetic code** for more stable regions, which they then targeted with the antibody **MEDI8852**.

Monoclonal antibodies are **similar to natural antibodies** but are made in a laboratory using **genetic engineering **techniques to mimic the activity of the immune system and aim at a target chosen by researchers. Specifically, the US virologists directed the monoclonal antibody MEDI8852 at the **stalk of the virus**, which is at the bottom of a protein called **haemagglutinin**.

****H5N1 bird flu: a treatment with up to 12 weeks’ protection****

As reported in ***Science***, **laboratory animals** (*monkeys and others*) were **pre-treated with MEDI8852** and were exposed to bird flu three days later, by means of an **aerosol **[**developed in 2023** by the same research team](https://www.upmc.com/media/news/092923-bird-flu).

None of the animals got **severe symptoms or died from the infection**. In addition, by trialling different doses, the scientists identified the **minimum effective concentration** to ensure **adequate protection**.

The duration of the protective effect is also interesting: **the antibody MEDI8852 was found to be effective for 8 to 12 weeks**, which is long enough to reduce the risk of falling ill in the event of an **outbreak of the virus**.

****H5N1 bird flu – are we ready to deal with a new emergency?****

**Possible future use** of MEDI8852 will probably not be available for everyone, however, as **monoclonal antibodies** are **extremely expensive** and need to be **injected** under **medical supervision**. What’s more, their production requires the use of **bioreactors**, of which there aren’t enough in the world to deal with a **large-scale epidemic**. But if the new drug is approved, it will be able to **protect the most vulnerable**, such as **people with a weakened immune system** or **healthcare workers**.

This study also shows that** lessons have been learned from the Covid pandemic** and that we could indeed be **better prepared** in the event of a new emergency. Virologists consider the** H5N1 virus **to be the most likely candidate for **spillover** – jumping from **animals to humans **and mutating until it becomes **transmissible between humans**. The scientific community is therefore already working on possible countermeasures: **monoclonal antibodies** to treat severe cases and **vaccines** to prevent them. Many laboratories around the world are hard at work developing **preventive solutions** to the H5N1 virus.

 

        

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