This report has been highly critical of the Stanford Covid-19 study, which essentially suggest that between 2.5% and 4.2% of people in the Santa Clara county have contracted COVID-19, which is 50 to 85 times greater than the number of cases being reported at the time.
I tend to think that the critics have been exaggerating. Sure the study is not randomly sampled; sure it suffers from self-selection bias (adjustable by weighting) and sure the antibody test kits were not as accurate as some that are available today. But still, no need to throw the baby out with the bathwater. As one of the earliest studies in the nation, it provided valuable insights and findings can be used as a reference for later studies.
Behind the high prevalence or high proportion of positive antibody test results, one other possibility or interpretation, in my opinion, is the issue with “Virus Density”. In other words, when an individual only contracts one or a few virus, it is easier for the immune system to deal with and one can walk away with no symptom at all. On the other hand, when one is contaminated with a high density of virus, like from repeated hugging, shaking hands, or talking to someone too closely, it posts a bigger challenge for anyone’s immune system!
This means social distancing still has its value, just to reduce the virus density in a locality. Keep in mind that virus density is likely to grow exponentially, and this is what makes the coronavirus scaring. By the same token, it also points to the high value and crucial importance of social distancing and shelter in place from early on, before the virus grows out of control, first on a few human bodies but then on a large herd!! Look at California and New York and you will see the value of early intervention.
One interesting difference: From what I learned from China and US, it seems there are far more asymptomatic people in the US than in China. If this impression holds true, the US diet of high protein (beef, eggs, milk, cheese, yogurt) versus China high starch diet (rice dominated) may have done the US a favor in strengthening their immune system? It would be one aspect to look at it when we have the time.
Of course, everything is a matter of degree. If you eat too much and become fat, you put a big burden on your immune system and reduce its efficacy. Also, based on my personal observation, your immune system is weaker when you travel to a new place, so stay home if you can.