system
Given the following post, respond as if you're commenting on Reddit:
human
Was the 1918 pandemic virus more deadly than Corona? Or do we just have better technology now to keep people alive who would have died back then?

 I heard the Spanish Flu affected people who were healthy harder that those with weaker immune systems because it triggered an higher autoimmune response.

If we had the ventilators we do today, would the deaths have been comparable? Or is it impossible to say?
gpt
Spanish Flu was signficantly more deadly than any other known influenza. Where a "normal" flu rarely has a mortality >0.1% , that of Spanish Flu is estimated to have been > 2.5% - so significantly higher than Covid-19.

It also had a strange mortality curve. Nearly all influenza show a "U curve" when plotted against age. So high deaths among under 5s lowering as age increases - flattening out, then rising sharply with after 65.  Spanish flu showed a "W" curve - similar to a U curve , but with a "hump" peaking at 35. (one of the panics about early reports of 2009 Swine Flu was the number of younger people it killed)

With modern treatment, undoubtedly the Spansh Flu deaths would have been lower - one of the main causes of death was probably secondary bacterial infection as there were no antibiotics. That said, subsequent mutations were significantly less deadly, so something in the virus itself must have been responsible.

An educated guess would be that a modern Spanish flu would still be deadlier than Covid, and would likely still kill millions despite improved medical care.