Well we don't really know that, because studies like this one seem to go out of the way to avoid directly studying that, or at least sharing the results. Inclu

Well we don't really know that, because studies like this one seem to go out of the way to avoid directly studying that, or at least sharing the results. Including whether exposure might result in any level of immunity without diagnosis of the disease or without having any obvious symptoms. But we do know they based their results on the existence of a positive covid test, and we know that people can test positive without knowing it, and without obvious (or any) symptoms that would suggest they were ever sick. So it would be nice if somebody included those distinctive subsets in one of these studies, especially since they're already including the data for other purposes.