Bird Flu Update as Antibody Therapy May Prevent Severe Illness

Antibody-based immune therapy could become a key weapon in the fight against bird flu after trials in monkeys successfully prevented severe illness and death from the infection. The preventative medicine works by targeting a relatively stable region of the bird flu virus, meaning it can withstand the evolution of possible new variants. "In our testing, the antibody performed beautifully," immunologist professor Douglas Reed of the University of Pittsburgh said in a statement. "This type of prevention can be very useful in controlling infection outbreaks and containing the bird flu pandemic." Bird flu is currently widespread among wild birds across the globe and is causing outbreaks in poultry and cattle. Since 2024, the Centers for Disease Control and Prevention (CDC) has reported 67 human cases of bird flu in the United States and one death from the virus. As the disease appears in more mammals—such as sea lions in South America and minks in Europe and China—experts fear that the virus is adapting to better infect and spread among mammals.

In their study, Reed and his colleagues demonstrated that a pre-treatment with their broadly neutralizing antibody, "MEDI8852," protected monkey test subjects from severe disease and death following infection with H5N1 bird flu. The monkeys were infected with H5N1 bird flu using small particle aerosols, enabling the virus to reach deep into the lung and better mimicking natural exposure. The team reported that serum levels of MEDI8852 remained high enough to afford the monkeys protection for some 8–12 weeks. The discovery opens the door to developing similar preventative treatments for humans—such that might be use, for example, to shield vulnerable populations from severe disease. "The antibody has already been tested in human clinical trials against human influenza viruses, so the development could be quite rapid," Reed told Newsweek. "It would not be useful for everyone, but could protect first-responders and individuals who came into close contact with patients infected with bird flu in an outbreak situation." In addition, he explained, the current research has also helped establish the testing threshold for antibody levels in blood, which will be useful for judging the immune protection generated by any future universal flu vaccine.

Read more

• Bird flu: Vaccines may drive virus evolution
• H5N9 bird flu outbreak: What are the symptoms to look out for?
• Bird Flu: Updated map reveals where virus is thriving

A key challenge in developing preventive medicine against influenza lies in how the virus can adapt rapidly to new conditions. This, for example, is why seasonal flu vaccines must be reformulated each year to match the current dominant strain. The researchers' solution broadly circumvents this problem. Paper author and University of Pittsburgh immunologist Professor Simon Barratt-Boyes stated: "This antibody is targeting a region that does not vary across different influenza viruses." "Think about it as a tree—different species have different leaves and crowns, but tree trunks look very much the same," he said. "Similarly, the stalk region of the bird flu virus closely resembles the same structure of seasonal influenza, which makes it possible for stalk-targeting antibodies to provide universal protection." With their initial study complete, the team are now both testing MEDI8852 against a new strain of H5N1 that is more closely related to the virus currently circulating among cows in the U.S., as well as evaluating a second broadly neutralizing antibody that might be used either alone, or in combination with MEDI8852. Do you have a tip on a health story that Newsweek should be covering? Do you have a question about bird flu? Let us know via science@newsweek.com.

Reference

Kanekiyo, M., Gillespie, R. A., Cooper, K., Guerra Canedo, V., Castanha, P. M. S., Pegu, A., Yang, E. S., Treaster, L., Yun, G., Wallace, M., Kettenburg, G., Williams, C., Lundy, J., Barrick, S., O'Malley, K., Midgett, M., Martí, M. M., Chavva, H., Corry, J., Treat, B. R., Lipinski, A., Ortiz Batsche, L., Creanga, A., Ritter, I., Walker, R., Olsen, E., Laughlin, A., Perez, D. R., Mascola, J. R., Boritz, E. A., Loo, Y.-M., Blair, W., Esser, M., Graham, B. S., Reed, D. S., & Barratt-Boyes, S. M. (2025). Pre-exposure antibody prophylaxis protects macaques from severe influenza. Science. https://doi.org/10.1126/science.ado6481