My wife's close friend works at Stanford. Her sister was recently contacted by Stanford, because she donated blood a few weeks back, and they detected antibodie

My wife's close friend works at Stanford. Her sister was recently contacted by Stanford, because she donated blood a few weeks back, and they detected antibodies for SARS-CoV-2 in her blood. The levels of antibodies were high enough that they requested that she donate plasma to help with other patients. She has zero symptoms. So the case that the infection rate could be much higher than expected is definitely plausible.