There are strong reports by WHO and CDC who have been in China that they are under-reporting what is actually going on.
That said, the speed in which the disease is spreading is a bit scary even if the media does seem to blowing this up. Corona does seem to be nastier than the strains prevalent in the US. In general, any flu can be nasty with maybe 31M Americans having the flu this year with 300,000 hospitalized.
On the whole, I'd rather the CDC be over blowing the threat than the opposite. It can take up to a year even on a fast track to get a vaccine up and running. We probably need to see what is going on in places like South Korea, Italy and Iran before running around like chicken littles. Personally, I just ordered some face masks on Amazon.