Emily Chung, Christine Birak, Marcy Cuttler, cbc.ca:

A closer look at people who tested positive for COVID-19 but never developed symptoms has found that such asymptomatic carriers have few to no detectable antibodies just weeks after infection, suggesting they may not develop lasting immunity.

There’s growing evidence that a significant proportion of people who test positive for COVID-19 never show symptoms, although it’s not clear what percentage of people that is and what role they play in spreading the disease.

I don’t recall precisely, but it seems to me that the conversation was not as much “well, herd immunity is a bad idea because we might not get immunity” but more so “herd immunity is assumed to work (we’ll get to immunity), but that will sacrifice too many lives.” But this report makes me think that the former question would have been the right one. Natural immunity may not even be on the table.