[Bon mots]

Stuck in their rooms while the recirculating air goes from room to room. I think that’s how the virus can spread.

I was thinking the same thing. They are sealed in a giant floating can with others that have been exposed and we don't know how a sealed AC system will affect the spread.

Could be a giant floating incubator for all we know.

[GBA]

It’s possible that the air circulation systems have some form of purification built in, perhaps similar to the UV purifiers used in home heating and cooling systems.

I’m sure this isn’t the first time a ship has had to deal with airborne contagions, so perhaps designers have learned to add systems and tools to help control such things.