We are underestimating, again, the true burden of H5N1 in humans
### Summary box The recent global spread of clade 2.3.4.4b H5N1 viruses has devastated poultry production impacting national and global food security. Though clade 2.3.4.4 viruses emerged prior to 2014,1 it was not until late 2020 that major outbreaks in domestic poultry were observed caused mostly by clade 2.3.4.4b H5N1 viruses.2 From mid-2021, a dramatic increase in activity and geographical distribution of these viruses occurred. The clade 2.3.4.4b viruses have been able to cross the species barrier to infect terrestrial and marine mammals contributing to an unprecedented infected species l...