I was thinking about that also, How many people felt like they had it based on symptoms and never got tested for antibodies?
Or maybe the antibodies were based on some other stuff ?
Wasn't there multiple versions of the virus ? From my understanding you can get both of them
I don't want to go down the can of worms that is the antibody testing, as it seems in most places, so far there are no confirmed cases being reported of those with antibodies.
Therefore, more likely than not that people extrapolated "herd immunity" from a skewed sample of the population.