A variety of insurers in the U.S., UK, Canada and elsewhere are starting to exclude coverage for the novel coronavirus COVID-19 from trip cancellation coverage, and even from some medical coverage.
Policies already written before this week are generally not affected, as the virus was considered an "unknown risk" similar to being injured in an accident or other reason that a cruise or trip might need to be delayed or cancelled. Now, however, the insurers are defining it as a "known risk," something you might expect to happen, and therefore not covered.
The rules vary by country and carrier; if you are holding or planning to buy travel insurance soon, check carefully with the carrier. For some, it might be a time to buy the more expensive "cancel for any reason" policies that some companies offer..