"https://www.fda.gov/media/164829/download
Here's the short FDA article if you'd rather start there.
I found the above while reading a JAMA article that scares the heck out of me, discussing the individual donor questionnaire above. Absolutely crazy.
Consider also that those taking PrEP feel bullet-proof and, as a consequence, expose themselves to much more risky sexual situations that they would have otherwise. The PrEP group has been proven to be at much higher risk for other dangerous STD's because they forego other secondary safety measures, such as condoms. So, instead of HIV, screeners have to be concerned about early syphilis, gonorrhea and chlamydia infections, many of which are quickly becoming antibiotic resistant.