WOW! The R0 of this virus appears to be insane!
You have a good point there! Great observation.
ETA
Your observation about R0 and age has me thinking....
Posing this as a question to anyone more familiar with viral transmission than I am.
As far as I know, the age of an infected patient generally comes into play with mortality rates. As far as I know, age generally doesn’t impact R0??
The R0 isn't a fixed number. It can be higher on the ship than in other conditions, and the location/environment is more likely to be the explanation for this massive R0 than the age of the persons on the ship.
I've heard it said that while R0 has a relation to the virus, but it also has a relation to human behavior and the environment in which the people are living.
The R0 of Ebola in the outbreak in West Africa was far higher than the R0 of Ebola in the UK or USA even though it was the same strain of the same virus.
Our responses to a virus outbreak can affect the local R0. Without contact tracing and isolation of those testing positive there would be a higher R0 in the UK, Canada, etc.
A hundred and fifty years ago couples often had six to twelve children, so even if they all stayed home, they're living in close quarters, and back then they didn't understand as much about hygiene either but even if they had, they'd still have a high R0. Back in those days, boarding schools and orphanages would have similar issues with massive R0 in that particular population. Nursing homes have a similar issue today. Schools and colleges and universities are known as good environments for spreading diseases (high R0).
I think the comparison of children to adult to elderly is complex. Oftentimes children pick things up very easily due to the high R0 conditions in schools and children's behaviour. So it can be possible for them to bring a virus home with them, get a fairly light illness but spread it to the parents and grandparents who then go onto get more severe illness. Perhaps there's an aspect where those who have a more severe case will shed more virus and for longer (as it takes their immune system longer to 'beat' the virus), but outside of a cruise ship or nursing home I don't think they would normally spread a virus as easily as children do.
And think about a child's behaviour not just with each other at school, but then when they come home. Smaller children are cuddled, their faces and mouths are kissed, they're not as good at covering their coughs and sneezes, etc. But often if a child doesn't 'feel' ill they'll just keep moving around performing these close behaviours that can spread the virus to someone more vulnerable.
So it's a highly dependent number that can be reduced with both government-level and personal actions.