At the very least, we have a current floor that 0.002% of the total Italian population has died from the disease so far; conversely, we know a minimum of 21,157 have contracted it in the same population, and 1,966 have recovered, so the mortality rate is probably less than 90%.

Now those two numbers are very far apart, so you might be inclined to wait and see whether the final number will lie, but the problem with that is, once the final number is known, it is too late to act.

We either have the option of acting now, as seems best with our current information, and correcting course as the new information reveals itself, or doing nothing at all, and waiting for better information, and our current information says that doing nothing at all is not the best option.