Disclosure of interest: I am a co-author on this conference abstract.
There seem to be two main themes in public discourse around HIV pre-exposure prophylaxis (PrEP). The first is that PrEP works. As in, PrEP is very effective at preventing HIV on an individual level, and PrEP is effective at preventing HIV on a population level. The evidence for individual-level effectiveness for men who have sex with men (MSM) is now very robust, with convincing data from several large studies in this population, including the iPrEX study, the PROUD study, and the IPERGAY study, just to name a few. These studies have shown that daily continuous PrEP provides close to 100% protection against HIV if individuals are well-adherent to this regimen, and similar levels of protection are afforded by event-based PrEP. Evidence for population-level effectiveness has been slower to emerge, but we now have convincing ecological data from San Francisco and New South Wales, showing large population-level decreases in HIV incidence in these jurisdictions since the introduction of PrEP (>50% in San Francisco and 35% in New South Wales). As is always the case with ecological data, PrEP cannot be given credit for the entirety of these decreases in HIV incidence, as both these jurisdictions also promote condom use, frequent HIV testing and early access to HIV treatment. But PrEP is the main change that occurred just prior to these incidence reductions.