I thought the tl;dr was we don't know for sure and we need to collect more data. "But the question remains — beyond these known clusters, how did the tens of t

I thought the tl;dr was we don't know for sure and we need to collect more data. "But the question remains — beyond these known clusters, how did the tens of thousands of Californians who aren’t accounted for in publicized major outbreaks become infected?" ... "“We don’t know if people just going to parks or beaches, just sort of casual social gathering, contribute a whole lot to infections,” Riley said. Public health officials “really need to identify the high-transmission settings and then target those and not have these unfocused measures on social distancing.”"