Prevention of HIV

Practical HIV prevention in 2024

• Core tools:
  • Daily oral PrEP (Truvada, Descovy) for HIV‑negative people at ongoing risk.
  • PEP: short antiretroviral course started within 72 hours after a specific exposure.
  • Emerging long‑acting injectable PrEP (cabotegravir every 2 months; lenacapavir every 6 months).
• Additional biomedical prevention discussed:
  • Vaccines: HPV (Gardasil 9), monkeypox, meningitis ACYW/B (B has partial gonorrhea protection), hepatitis A/B, plus routine childhood vaccines.
  • DoxyPEP: two doxycycline pills after sex to cut risk of syphilis, chlamydia, and partially gonorrhea.
• Many note clinics and sexual health services can guide people on PrEP/PEP and broader risk reduction.

U=U (Undetectable = Untransmittable) and viral load

• Several comments emphasize strong evidence that people with consistently suppressed viral load do not sexually transmit HIV, citing large trials in both heterosexual and gay couples.
• Viral-load thresholds are discussed: <200 copies/mL linked to no observed transmission; untreated semen can carry 10,000–1,000,000 copies/mL vs. 1–10 on treatment.
• A minority of commenters question absolute claims of “zero risk” on theoretical virology grounds; others counter that empirical data overwhelmingly support U=U.

Lenacapavir specifics

• Described as a capsid inhibitor that binds HIV p24 and blocks multiple life‑cycle steps (nuclear import, assembly, capsid formation).
• Given as a subcutaneous depot with very long half‑life (on the order of months), attributed to structure and poor solubility.
• Phase 3 prevention trial in ~5,300 high‑risk participants: 55 infections in oral PrEP arms, none in lenacapavir arm; trial stopped early for efficacy.

Resistance and mutation

• Some argue dual‑mechanism or combination regimens make resistance “difficult but not impossible,” noting HIV’s very high mutation rate and need for multi‑drug therapy in treatment.
• Others downplay resistance risk for PrEP, citing long experience with Truvada/Descovy and lack of major resistance problems so far.

Side effects and safety

• Trial reportedly showed excellent short‑term safety; halting was framed as due to both high efficacy and acceptable tolerability.
• Skeptics worry early stopping can exaggerate benefits or miss rare harms; others cite analyses suggesting early stopping is not systematically misleading.
• Long‑term effects of very long‑acting agents and PFAS‑like chemistry are raised but remain unclear in the thread.

Cost, patents, and access

• Strong expectation lenacapavir will be priced at a premium, following Truvada/Descovy patterns (high US list prices despite cheap generics elsewhere).
• Debate over whether high prices are justified by R&D vs. driven by patents, marketing, and oligopolistic behavior.
• Multiple comments note:
  • Government and universities often fund early research and, in PrEP’s case, major trials.
  • Industry pays for most large clinical trials and commercialization.
  • Patients and insurers bear high costs, with especially severe implications for low‑income countries; many foresee reliance on Indian generics for African access.

Behavior, risk groups, and non‑HIV STIs

• Discussion of PrEP use in gay/bi men, sex workers, people who inject drugs, and young women in high‑incidence African settings.
• Some worry “lifestyle PrEP” encourages condomless sex; others argue:
  • People already forgo condoms, especially for oral sex.
  • Other STIs are typically treatable, whereas HIV is lifelong.
  • PrEP users tend to test frequently and may be less likely to transmit STIs overall.
• HSV and some other infections remain difficult to prevent fully; condoms only partially help.

Public vs. private roles

• Extended debate on:
  • True cost of drug development (including failed candidates).
  • How much of foundational science and clinical work is taxpayer‑funded.
  • Whether life‑saving drugs should be for‑profit, price‑regulated, or publicly developed.
• No consensus; many agree that current patent‑driven, high‑price model limits access, especially where HIV burden is highest.