"...so the virus is probably spreading silently" And harmlessly? Because the outbreaks in Iran and Italy show that the virus, if not contained, will spread rap

"...so the virus is probably spreading silently" And harmlessly? Because the outbreaks in Iran and Italy show that the virus, if not contained, will spread rapidly and start killing hundreds every day. Why exactly is this not occurring in Japan? How do we reconcile the idea that Japan is doing little-to-nothing about the virus with the fact that the virus is not causing nearly the same level of illness or disruption as in other countries?