_Although I normally prefer not to speculate, there is something strange/interesting with all the covid-19 infections & deaths that has also been noticed by Michael Levitt in his extensive stats - every single hard-hit region saturates in a few weeks.

It's unlikely all those countries magically found the right measures just after the spread accelerated, so it's likely rather related to the infection itself. Either we underestimate immunity through the RNA-tests of active infections, or some people are less susceptible.