I have a background in infectious disease research. From what I know, with this particular virus, it would be more surprising if the dose-severity dependence hy

I have a background in infectious disease research. From what I know, with this particular virus, it would be more surprising if the dose-severity dependence hypothesis was true than if it was not. There has been a lot of discussion of this hypothesis lately, but I am aware of exactly one experimental study that came anywhere close to proving it. That study dosed mice with a nasal titer ladder of flu and observed severity variations. Even that study failed to establish the dynamic range necessary to demonstrate dose dependence (the mice went from all survived to all dead in a single step of the titer IIRC). There are certainly plausible mechanisms for the dose severity dependence hypothesis to be true, but with fast-replicating viruses I think the parsimonious assumption is transmission chains are dominated by a single event.