I have only non-expert lay person understanding of this virus and how it transmits, so don't jump on me if this is stupid, but a question has occurred to me. Could there be a genetic component to this, as in some groups of people are more susceptible than others? This might explain why Italy has such a high infection rate, and also why Australia (which has a large Italian immigrant population) seems to have a higher rate than we do. I am not speculating about this, just asking. Can anyone explain?
Some statistical analysis coming out of China now suggests bloodtype may have some effect on it. Type-A being slightly more susceptible and Type-O slightly less so. There has been no explanation why this might be the case and people are surprised by the correlation as this virus mostly attacks the lungs and is not blood-borne. It is only a weak correlation but is above the expected random fluctuations in the sample.