old meaning the majority, with anything, there will always be exceptions.
While that may be the case now, it doesn't mean it will be the case two months from now as more and more "outliers" (I say
outliers as they are the minority of what you did mention) will pop up. Furthermore, I believe that this is just the beginning, in Okinawa, and around the rest of the world, too.
With cases appearing in Egypt and Africa today, all that we know about the virus is out the window.
Such as the case with temperature. It was believed that in hotter weather, it'd be blown over. But, the spread in Singapore clearly debunked that as it lies on the equator.
I don't think we can definitively say that it only affects the old or immunocompromised more than healthy people until there are more facts and statistics shared from China. This is because
doctors and other medical workers in full protection are becoming ill from the Wuhan coronavirus, and they're not the oldest, either. It is debatable whether they came in contact with it prior to their official duties, though.
A Harvard professor says that
the spread of COVID-19 is just beginning and gathering steam as well. I tend to lean with his opinion until statistics are more transparent to say otherwise.
I'm not here to fearmonger or scare, but, just present the facts as they come out.
The only thing the rest of the world can do is lay in wait.
Hopefully, everyone can be hygienic in the meantime while the anti-virus is being developed, tested, and distributed as this thing has already surpassed nearly the total of deaths of both MERS and SARS combined. This is even with its low fatality rate of 2% compared to MERS and SARS at 36% and 9.6% respectively: the concerning part is the unknown with the addition of the incubation period of COVID-19. So, it's not something to be taken lightly in my opinion.