OFFLU Avian Influenza Vaccine Matching (AIM) For Poultry Vaccines: H5Nx Executive Summary

This document provides the October 2024 OFFLU Avian Influenza Matching (AIM) Executive Summary, which reviews antigenic characteristics of Gs/Gd-lineage A(H5Nx) viruses—focusing on clade 2.3.4.4b and its global dominance, alongside clades 2.3.2.1a and 2.3.2.1c/h—using harmonised HI assays, antigenic cartography, and vaccine challenge studies, emphasising region-specific drift in poultry populations and the need for updated or multivalent vaccines where multiple clades co-circulate.