NYTimes: Cuomo Says 21% of Those Tested in N.Y.C. Had Virus Antibodies - this raised some potentially very big questions

If correct, could this imply that there is a huge population of asymtomatic carriers among us?

Cuomo Says 21% of Those Tested in N.Y.C. Had Virus Antibodies: Live Updates https://nyti.ms/3byGy6X