In the last month almost 1% of the current population of the earth quarantined in China [0].
What exactly worries you about mass hysteria and panic? Why would that be worse than what is likely to happen as Covid-19 spreads outside of China?
I'm all in favor of not overselling the danger; but this virus is a real concern. I mean, unless someone has a very good argument why Hubei are somehow special and it can't happen again elsewhere everyone should be stocking up on supplies in case they are caught in a serious quarantine. The actions taken don't seem to be stopping exponential growth of this virus; if anything all that seems to be actively measured is how good countries are at producing testing kits.
> Only a small fraction die: The current fatality rate hovers around 2%.
If 2% of the people I know died this year, that would be the worst disaster in my country in my lifetime.