No direct evidence. But any reasonable parameters for the viral reproductive number and mortality, along with clear evidence of asymptomatic carriage, lead to this inevitable conclusion.
To be fair, I agree the expected case to death rate is less than one percent normally. The questions this leads to, is why it is higher on Italy? Either in reach of infection, or in deaths?
This article implies their infection to death rate was already elevated for the flu. Most accept this is, at best, a deadly flu. That would strengthen this hypothesis.
But your hypothesis seems to be there are more infected in Italy than elsewhere. But you then have to explain why it did more there.
If we have infection to death rates in all countries, that would let us predict if the first hypothesis is true. To test yours? What can we do?
I don’t think there is anything special about Italy, they just started earlier than other countries (1st cases were 3 weeks before other Euro countries) and in some provinces didn’t take it seriously.
Per another thread, the US has to start seeing the numbers they have had to date every two days for this to be worse then last year's flu. Per this article, Italy has to continue with their current pace to hit last year's numbers. For another few weeks.
Let that sink in. Italy had 25,000 deaths attributed to flu like illness two years ago. They are at 6000. Accepting that this is a hard flu like virus, we would expect them to have bad numbers. Why? What is so bad about Italy?
Again, comparing to the flu is not minimizing. The flu is already a terrible virus.