https://www.thebodypro.com/article/whos-prepared-to-make-prep-work
    Figure 1. Adherence Matters in PrEP Impact
    Figure 1. Adherence Matters in PrEP Impact When tenofovir and/or FTC could be detected in plasma of Partners PrEP3 or iPrEx2 participants randomized to study drugs (versus placebo), calculated protection from HIV infection was higher than in overall protection results in those trials.
    Figure 2. Theoretical Infection-Exposure-Resistance Relationships
    Figure 2. Theoretical Infection-Exposure-Resistance Relationships Left: If someone taking TDF/FTC PrEP misses too many doses, drug levels will fall and that person may become infected with HIV. But facing little or no TDF or FTC in the newly infected person, the virus will not be pressured to evolve to mutant strains resistant to TDF or FTC. Right: If a person takes TDF/FTC PrEP regularly, levels of the drug will be high enough to prevent infection -- and without virus there can be no resistance. Center: But there may be a "zone of resistance risk" between low and high TDF/FTC levels that permits infection at drug levels still high enough to select resistant virus. (IllustrationJohn Mellors, University of Pittsburgh.
    Figure 3. Modeling 10-Year PrEP Impact on Resistance Prevalence and HIV Prevention
    Figure 3. Modeling 10-Year PrEP Impact on Resistance Prevalence and HIV Prevention Optimistic, realistic, and pessimistic PrEP scenarios (see text for explanation) would have dramatically different impacts on additional prevalence of resistant virus in that population 10 years after PrEP rollout, according to results of a modeling study by Cleveland Clinic researchers.39 The relative impacts on HIV infections prevented would be equally striking.
    Figure 4. Three Options for Future PREP Agents
    Figure 4. Three Options for Future PREP Agents Researchers are hard at work devising and testing PrEP agents that could improve on the activity, durability, and tolerability of TDF/FTC. (Pill and needle/syringe photos from Wikimedia Commons. Intravaginal ring photo from International Partnership for Microbicides.

    Mark Mascolini

    Mark Mascolini writes about HIV infection.

    The Center for AIDS Information & Advocacy

    The Center for AIDS Information & Advocacy