Ake, the CDC's statistics are not that incontrovertible.

"As a result of an increase in false positive rates with rapid oral HIV testing in 2005, New York City's Department of Health and Mental Hygiene added the option of testing finger-stick whole blood after any reactive result, before using a Western Blot test to confirm the positive result. Following a further increase of false positives in NYC DOHMH STD Clinics during the end of 2007 and beginning of 2008, their clinics opted to forgo further oral screenings, and instead reinstituted testing using finger-stick whole blood.

"Despite the NYC DOHMH discontinuing oral screening due to the false positives, the CDC still continues to support the use of noninvasive oral fluid specimens due to their popularity in health clinics and convenience of use."

Source:

Burke D, Brundage J, Redfield R, Damato J, Schable C, Putman P, Visintine R, Kim H (1988). "Measurement of the false positive rate in a screening program for human immunodeficiency virus infections".
--The New England Journal of Medicine, issue 319.

Don Firth