"Majority of New Yorkers were not infected" is not enough to say they don't have herd immunity. Wasn't there a study showing 40% of people have generic coronav

"Majority of New Yorkers were not infected" is not enough to say they don't have herd immunity. Wasn't there a study showing 40% of people have generic coronavirus anti-bodies from prior colds and it is believed that these help? Though the extent might not be known.