[cemregr]

The standard HIV test people do (ELISA) tests for the antibodies produced against HIV, not the HIV strain itself.

Donated blood is tested with PCR, which detects the HIV RNA. PCR test detects HIV in as quick as a couple of weeks.

However, because of the added cost (and time cost) of running PCR tests, donated blood samples are pooled before being tested. If the test runs positive, samples are tested individually.