We’ve known since at least March that about 10 human cases of this new bird flu would allow the virus to mutate and adapt to humans. This is the 14th reported case in the states this year, and the first which could have been transmitted from human to human. We understood what was happening, yet have really done nothing to try to prevent it’s spread.
The mutation rate baked into Influenza’s reproduction cycle is much more elaborate than coronaviruses, and this isn’t exactly a bad thing. When a human catches bird flu from a bird, the mortality rates are pretty burly as this version of the virus attaches to the α2:3 receptor. While this receptor is found throughout the avian digestive and respiratory track, it’s only found in the lower lungs of humans. A lower lung infection will always be gnarlier than an upper respiratory infection. Human influenza viruses have a preference for the α2:6 receptor, which is found throughout our airway. This is the primary adaptation which occurs when influenza mutates to infect humans. But a virus is a parasite, so in their ideal world, they wouldn’t kill their host. Viruses often do the most damage when adapting to or having recently adapted to a new host. Hopefully, the mutation rate of influenza will result in a shorter pandemic compared to COVID if it ends up taking place.
Then why does bird flu have more invasive symptoms and a higher mortality rate compared to human influenza’s? I was taught by a virologist who’s been around the block many times and got her PhD in the USSR. She was adamant that a parasite never wants to kill it’s host, as this results in no longer being able to reproduce in the host and shortens it’s reproduction time in future host.
Most viral offspring are not capable of infection, as without mutations, viruses would not be able to reproduce effectively and could not adapt to changing environments. To disprove a hypothesis simply means one aspect of the statement is incorrect. So while the cause and effect occurs, the explanation for why wasn’t dialed. Or at least, this would be my guess for how it could have been disproven.