The article's answer to this seems to be: 1) over the last 20 years H5N1 has spread from birds to minks and cows and in the last few months also to pigs 2) pi

The article's answer to this seems to be: 1) over the last 20 years H5N1 has spread from birds to minks and cows and in the last few months also to pigs 2) pigs in particular are hosts to both human and bird viruses, so they're a likely place for an H5N1 virus to do the reassortment with a human flu virus that might make it become human to human transmissible 3) but nonetheless, today is still not that much different -- the risk now is only a little elevated from the baseline ~5% risk of some pandemic flu breaking out that we might get in any year