There I was feeling quite comfortable a few weeks ago, I'm youngish, generally healthy but my immune system over-reacts, I have several allergies, a couple of autoimmune conditions and mild asthma. I thought my over active immune system would kick in and fight Covid and apparently it does but then it doesn't know when to stop and can create a Cytokine storm which is the thing that causes the damage. There doesn't seem to be a lot known about it.
www.nytimes.com/2020/04/01/health/coronavirus-cytokine-storm-immune-system.html