@Prevenger17
Actually do have an example of what I mean.
Years ago a friend of the in-law family went into hospital with failing health and whilst recovering in hospital he died with swine flu.
Except he wasn't in hospital for anything to do with swine flu , no symptoms of it , was his own health that was failing him to begin with. He caught swine flu it seems whilst in hospital and that is why it was put down as cause of death.
And swine flu was just as much a real thing , it just only appeared at the last minute before he passed.
Key word there being: recovering.
So yes, swine flu was the cause the same way COVID-19 is currently the cause for lots with failing health.