The HIV/AIDS Establishment — Big Pharma, NIAID, etc. etc. — is assiduously promulgating the idea that healthy individuals who engage in sex should imbibe highly toxic substances so that they will be less likely to become “HIV-positive”.
This illustrates how true believers and those with vested interests are able to bias clinical trials to deliver desired results even when much earlier data already established that the desired results cannot have been obtained honestly: for example, several trials of tenofovir to prevent “HIV infection” managed to report that serious adverse events from tenofovir were no more common than from placebo, even as it has long been established that tenofovir causes kidney failure and other harm.
Since this illustrates general flaws in medicine and science, I posted the full analysis on my scimedskeptic blog rather than here; see When prophecy fails.