And this came out today as well:
NEW YORK (AP) — More evidence is emerging that far more New Yorkers have had the coronavirus than the number confirmed by lab tests, officials said Thursday. A state survey of about 3,000 people found that nearly 14% had antibodies, suggesting they had been exposed to the virus, Gov. Andrew Cuomo said at his daily news briefing. In New York City, the epicenter of the pandemic in the U.S., 21% of the people tested had antibodies.