[yawpitch]

Feel the need to point out that before it made the evolutionary leap to ready human-to-human transmission there was no reason to suspect what would become SARS-CoV-2 of being capable of causing long-term effects either.

We have no real idea what a highly human-to-human infectious novel H5N1 variant would do in humans, long-term, precisely because we haven’t infected enough people with it to find out.

[princearthur]

This is true. However, we've had zoonotic spillovers since before the dawn of civilization, and the Covid pandemic stands out in modern times in the ways I listed.

There's no reason to suspect the next pandemic will stand out in the same ways, or as much in general, particularly if it's Influenza.

[yawpitch]

The 1917-1918 flu pandemic also stood out for the many novel short-term and long-term effects, most of which we are still learning about because records and data collection were so poor. Every new spillover is an opportunity to learn what can happen that was not captured in our very bad memory of such events, effectively none of which have been rigorously recorded until the mid-20th century.

There is, in other words, no reason to suspect any particular outcome. Given how poorly we handled the still-ongoing SARS-CoV-2 pandemic there is zero reason for optimism.