Indeed doctors, epidemiologists and other health experts have been saying for several weeks that the coronavirus is being spread in part (perhaps in large part) by so-called “super spreaders” who either have no symptoms or such mild symptoms they didn’t realize they had the disease. Only widespread random testing for antibodies, indicating someone had Covid-19, will reveal the true case total. I wrote more about that here: Nobody Has a Clue How Many People Have COVID-19.