David, because it is so highly infectious, the numbers increase at an unbelievable rate from day to day. Italy went on lock down because people were not obeying the quarantine orders, and spreading the virus by moving around. Especially going from the better equipped north to the poor south, where there had been no cases.
The two categories most at risk are the elderly, and those who have other existing pathologies like cancer, pneumonia, etc, which make it very difficult for their systems to fight off the virus. It is said these patients don't die of the virus but also of the virus.
However, we are seeing more and more younger cases here. In the UK a new born was diagnosed with Coronavirus.
Added to this basic situation is the lack of ventilators for those who's respiratory systems have been compromised by the virus.
The younger are not protecting the old.
Obviously the medical staff are not old, although doctors in retirement have volunteered to return to service to help because of the shortage.
Unfortunately many youngsters were taking it very lightly with the attitude that they are not at risk, and were still gathering in groups, then going home and potentially infecting their parents and grandparents.
In addition, while the mortality rate of the virus is lower than that of the flu, the numbers are higher, so logically the result of a lower percentage of a higher number gives you many more numerical deaths.