>if we do take a step back and look at the influenza model - in other words, does that tell us anything about what might be happening here, realizing this is a coronavirus and not influenza? We have never understood why, in previous influenza pandemics - and there have been 10 of them in the last 250 years - do you see cases occur in the first several months of what we call a first wave. And a wave being defined by peaks of cases and then literally a trough where cases, in a sense, almost disappear. We've seen that in all the previous influenza pandemics. That disappearance may last for two or three months and then we see a big second peak. We have no idea why the first peak occurred. We have no idea why they go away. We have no idea why it comes back. And then a second wave ends, too.
I think the OP picture is why this happens. The pandemic starts and scares people so they act carefully to stop the spread. This causes the trough. Then a few months later people relax and stop worrying about the virus. This allows the virus to spread again.