False positives in HIV tests

A promising new oral HIV test that uses fluid swabbed from the mouth to quickly and easily detect the virus that causes Aids incorrectly diagnosed a quarter of the people who tested positive in San Francisco, city health officials have discovered.

Forty-seven people who tested positive after using the OraQuick Advance HIV test in city clinics were not infected at all, the San Francisco Department of Public Health said, The San Francisco Chronicle reported.

Investigators learned of the errors after follow-up blood screenings gave the patients a clean bill of health, and health officials stopped using the test at City Clinic, the health department's primary testing location for HIV.