You can generally infer it from restrictions in places that had high case counts and then enforced stay at home measures. Looking at the per-day growth rates in

You can generally infer it from restrictions in places that had high case counts and then enforced stay at home measures. Looking at the per-day growth rates in NYC, Italy, LA, etc. before and after the instantiation of stay at home measures is pretty convincing. We'll probably have some more data as places start to reopen.