See this maritime-focused article, China isolates port in Wuhan. Cruise lines cancel trips from China.
The potential economic impact to China is already happening. What would happen here in the United States if you closed schools for several weeks? Seattle has approximately 1.2 million cruise passengers each cruise season. Take the income from that and it adds up quickly if no ships were docking. Each ship docking creates $4 million in additional economic activity for the region.
The general message I am reading is that the ordinary flu is more dangerous. In China they are not reacting as if that were true.