A Nature Communications team isolated and characterized human monoclonal antibodies that neutralize clade 2.3.4.4b H5N1 hemagglutinin. The antibodies displayed broad-binding and potent neutralization in vitro, and structural mapping identified conserved epitopes on hemagglutinin that explain their cross‑reactivity. The work supplies candidate therapeutic mAbs for severe avian influenza and provides epitope data useful for vaccine design and stockpiling. Public‑health agencies and biodefense programs may use the antibodies and structural insights to accelerate countermeasure pipelines against H5Nx threats.