Fair! I was imprecise. I was talking about H5N1 while saying "bird flu" and I would change "There's any number of zoonotic diseases that are a mutation or two away from infecting people" to "There's any number of zoonotic diseases that are a mutation or two away from mass infecting people."
For instance, one reason previous versions haven't taken off across people is because they are good at replication at 40C(bird respiratory tract), but don't replicate well at 32C(human respiratory tract).
https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1000424
I've pointed this one out a couple of times just to get thinking about how it's not just receptors. There's physical differences in different hosts that have to be overcome as well. It's a multi-step process for the virus.
"Bird flu" as a general term now, was first discovered in 1878. The next mutation could be the one, or it might not be. The step to more mammalian spread, first reported in 2022 and studied in 2023 was a big deal. We'll see what's next.
