> It never translates it's RNA and since RNA is fundamentally less stable of a molecule than DNA, you get really high mutation rates. That "instability" is caused by the lack of a built in error checking mechanism in RNA.
The coronovirues have a proofreader mechanism, which is interesting.
Yep! That's what really makes influenza special, as I said the mutation rates are only part of why Influenza viruses rapidly change. Their ability to cross between species by combining easily with other types of influenza viruses are the key to their incredible variability
One of the distinguishing trait of CoVs are their special RNA replication/transcription mechanisms that results in less errors, which is really important considering the large size of their genomes compared to other RNA based viruses. Though, and correct me if I'm wrong, aren't they still extremely less stable than DNA viruses? Which is why only short/medium term immunity is usually possible? I don't know a lot about the synthesis of coronavirus RNA but it looks super interesting
> Though, and correct me if I'm wrong, aren't they still extremely less stable than DNA viruses?
That's correct. Worse, the proofreader doesn't have to protect all parts equally...
> Which is why only short/medium term immunity is usually possible?
No. For some viruses active immunity just doesn't last particularly long for reasons we don't understand (or at least it was described as not understood in every paper I've seen on the subject). For some viruses you can be reinfected months later with exactly the same virus. This is the case for several cold causing viruses.
The coronovirues have a proofreader mechanism, which is interesting.
And influenza has more potent evolved countercountermeasures than just high mutation rates: https://en.wikipedia.org/wiki/Antigenic_shift