In conclusion, the molecule described in this paper is a singular human mAb featuring a broad heterosubtypic neutralizing activity encompassing group 1 and group 2 influenza A subtypes, and therefore recognizing a broad-range neutralizing human B epitope in the stem region of HA. Indeed, PN-SIA28 neutralizes influenza viruses belonging to all subtypes that have caused pandemics in humans, as well as other subtypes with pandemic potential.