This one is pretty easy to make into a story.
What if they were left at sea while the rest of the country dealt with an outbreak? Who would emerge as a leader? What would they do for food?
This could be lord of the flies on a cruise ship.
Create similar characters and have them face challenges exclusive to a ship at sea.
Of course, those with the virus would have to be dealt with. In the beginning, there could be government aid. Then, once the government cut off support from the ship because of the requirements by its own citizens, the fate of those people would have to be dealt with.
One faction could choose to leave them to their fate or even remove them from the population to save resources.
The other faction could decide to try and save them, succumbing to the disease themselves.
The cruise ship could be large enough to allow for a complete separation of the two populations.
The theme could be the role community plays in any society.
Sequels could see the ship traveling the seas, stopping at islands to set up new living spaces, and the results of coming into contact with the island’s inhabitants.
Then, they could take to the seas once more like pirates, surviving on the supplies of other ships. The islands could provide new, healthy individuals. Or people with immunity.
Since kids aren’t as susceptible to the disease, this could be a story world where all the world’s elderly are eliminated, leaving kids to take up the responsibilities now required by young adults. The workforce would get younger, and they would be responsible for taking care of the sick because they aren’t as easily affected.
In fact, this could be the reason the faction on the first ship survived: they took all the children, not seeing them as resource drains, and used them to help provide healthcare.
The beginning of this story already happened because of the coronavirus spreading throughout the world. A ship outside the U.S. was placed under quarantine by U.S. officials and forced to stay at sea for six extra days. The order came after numerous people were found to be infected with the coronavirus.
The quarantine ended when the ship was allowed to dock in Oakland. The passengers are required to be kept under federal quarantine for another two weeks.
There were reports of food shortages, with one passenger saying they have to “fight for rotten food.”
