If they have been in isolation more than 14 days, how are there new cases? There is speculation that the virus may be active in some people who never show symptoms and act as carriers.
It occurs to me that if you're in a cabin without a balcony, all of your air is circulated through the ships central HVAC system. So, if someone is sick and coughs, there may be a slight probability that the particles they shed may make it to another room through the ventilating system.
It also occurs to me that everyone is being fed through trays delivered to the cabin door. No matter how hard cruise ships try to sterilize the kitchens, every month or so there's a mass outbreak of norovirus. Couldn't food be a transmission vector for this virus, too?
Could be a spouse to one already infected. I know there was an American who had it early, but his wife didn’t at the time. I’m wondering if she got it.
There is a long incubation period. The only way to make sure no one else is infected is to keep everyone on board for 14 days after the last known infectious person was removed.