It would be more accurate to state "levels off before 10-20% develop antibodies". The author wrote an article that covers other mechanisms by which the human i

It would be more accurate to state "levels off before 10-20% develop antibodies". The author wrote an article that covers other mechanisms by which the human immune system can fight viral infections. The definition of what 'infected' means is a total gray area. The human body is constantly fighting low-level viral infections. PCR positive doesn't mean you are seriously infected or an active 'spreader'... just means they found some viral RNA in your mouth/throat/nasal-passage. Just means you were definitely exposed and are carrying the virus. Many of those cases were completely/almost asymptomatic, right? N. Italy is it's own unique situation... don't have specific comments there... With an enclosed dense population situation like a prison or a naval vessel... it is interesting that the spread would stop short of ~100% infection once it crosses the 25-50% threshold, given what we understand of the overall high transmissibility of this virus.