"It is theoretically possible that socioeconomically privileged individuals really do lack some immune-response mechanism that protects individuals who have been exposed to a wider array of infectious pathogens. (A recent report on COVID-19 surveillance testing at a Boston homeless shelter contained the stunning disclosure that 36 percent of 408 screened individuals tested positive for COVID-19. Yet the vast majority were asymptomatic, and even the few who were symptomatic did not diverge statistically from the 64 percent of tested individuals who were COVID-19-negative.)"

Interesting. Having spent some time in SF, can attest that the homeless - on occasion - appear to have super human immune systems.