While this is great information, a few facts will still confound attempts to speculate based on this number: - The production of IgG antibodies is mostly delayed until after an infection is cleared. - This is a random sample of people who were outside, it's not representative of the total population. - Non-trivial numbers of people may never develop detectable antibodies for SARS-CoV-2: https://www.medrxiv.org/conten…
Also it looks like they chose people with symptoms (i.e. "COVID-19 patients"). Would we expect the amount of detectable antibodies to be less, more, or the same among asymptomatic/mildly symptomatic people, or do we not know?