You have a great career ahead of you as a writer of fantasy novels Tony.
If there’s no immunity for ‘flu (which is currently killing more people per day than COVID — 19,) there wouldn’t be any point getting vaccinated would there? Vaccines work by exposing our bodies to a mild form of the disease so the immune system produced antibodies. Thus when the immune system encounters the real illness it already knows what antibodies to deploy.
But you respond to me as if I am a naive young guy who deludes himself he is immune to influenza because he’s never had it. No, I’m over seventy, I think if I was going to get the infection it would have found me by now.