His brother has been locked up for months too. He had no symptoms. This past Shabbos he had Yahrzeit and sat together with me at the farbrengen where we heard what I described above from a senior Hatzolah member.
which is why I am advocating that when those senior hatzalah people/doctors give guidance we should listen, not pick and choose the parts we like (everyone is safe) and discard the parts we don't like (continue SD measures, no kiddushim in shul, continue to prefer outdoor events, get a handle on indoor weddings/no visitors/etc.)
My other point is: herd immunity isn't zero. there are some (few), vulnerable victims, some (few, outside) sources of infection, and some (few) un-immune local carriers (me). it would do us well to maintain some small degree of precautions, whatever our local experts are suggesting (they've been wrong. אתה צודק. please אל תהיה צודק תהיה חכם). I don't know about you, but I lost enough relatives this year.