[ivyleaguebrat]

"That means that the PPV is 4/6 = 0.66, so one-third of all people who would be tested under this plan will test positive even though they are really HIV-negative."

You mean one-third of people who will test positive are actually negative. Since the number of people testing positive is pretty miniscule (6 in 1000), I don't think that's unreasonable. More tests would be done to eliminate rule out false positives.

[riverdawg]

"Since the number of people testing positive will be pretty minuscule ..."

(6/1000)*230,000,000 = 1,380,000 will test positive, and 460,000 of these will be false positives. Scaring the hell out of about a half-million people, almost all of whom have zero risk factors for HIV infection, and then subjecting them to additional (e.g., ELISA) testing - which *is* expensive - doesn't seem to be very wise public policy to me. Most of us, by virtue of our genetic makeup, have essentially zero chance of passing on Tay-Sachs disease (mainly afflicting Ashkenazi Jews) or sickle-cell anemia (mainly afflicting those of West and Central African descent). Do you advocate mandatory genetic testing for these traits for all prospective parents?