Yup good catch about the old source, I removed that from my comment. The source provided by animats puts the seroprevalence at 21.6% for the U.S. I think that

Yup good catch about the old source, I removed that from my comment. The source provided by animats puts the seroprevalence at 21.6% for the U.S. I think that should be a lower bound of the number of individuals who have been infected, given antibody levels wane over time (even though immunity does not necessarily wane).