HIV prevention strategies

PrEP & PEP - Chemical Shields Up

• PrEP (Pre-Exposure Prophylaxis): Ongoing ART for high-risk individuals to prevent HIV.

  • Regimen: Daily oral tenofovir/emtricitabine (TDF/FTC or TAF/FTC).
  • Indication: For individuals with ongoing, substantial risk of HIV exposure.
  • Key: High adherence is critical for >99% efficacy in preventing sexual transmission.

• PEP (Post-Exposure Prophylaxis): Emergency ART initiated after a potential HIV exposure.

  • Regimen: 3-drug ART course (e.g., TDF/FTC + dolutegravir/raltegravir).
  • Duration: 28-day course.
  • Crucial Timing: Must be started as soon as possible.

⭐ Initiate PEP urgently, ideally within hours of exposure, but no later than 72 hours. Efficacy declines significantly with delay.

Barriers & Behavior - Smart Choices Save

• Physical Barriers:
  • Condoms (male/latex, female/polyurethane): Emphasize consistent & correct use for preventing sexual transmission.
  • Harm Reduction (IVDU): Advise using sterile needles/syringes and avoiding equipment sharing.
• Behavioral & Procedural:
  • Risk Reduction Counseling: Encourage limiting sexual partners and knowing their HIV status.
  • STI Screening: Promptly diagnose and treat other STIs, as they can ↑ HIV transmission risk.
  • Voluntary Medical Male Circumcision (VMMC): Reduces female-to-male transmission risk by ~60%.

⭐ Co-infection with other STIs (e.g., syphilis, herpes) significantly increases HIV transmission risk by disrupting mucosal barriers and causing inflammation.

Treatment as Prevention - Undetectable is Untransmittable

• Core Principle: Antiretroviral therapy (ART) suppresses HIV viral load to undetectable levels in the blood.
• Definition of Undetectable: Plasma HIV RNA level below the limit of detection of standard assays (typically <20-75 copies/mL).
• Clinical Implication: A person with a sustained undetectable viral load cannot sexually transmit HIV to others.
  • Mnemonic: 📌 U=U (Undetectable = Untransmittable).
  • This requires consistent ART adherence for at least 6 months to ensure stable viral suppression.

⭐ High-Yield Fact: The landmark HPTN 052 trial demonstrated that early initiation of ART by HIV-positive individuals reduced sexual transmission to their HIV-negative partners by 96%, cementing TasP as a cornerstone of HIV prevention.

Perinatal Prevention - Protecting the Newborn

• Universal HIV Screening: All pregnant women at the first prenatal visit.
• Maternal cART: Initiate combination antiretroviral therapy immediately for all HIV-positive mothers to reduce viral load.
  • Goal: Achieve undetectable viral load (<50 copies/mL) before delivery.
• Intrapartum Care: Decision based on maternal viral load near delivery.
  • Viral load >1,000 copies/mL: IV Zidovudine (ZDV) + scheduled C-section at 38 weeks.
  • Viral load <1,000 copies/mL: Vaginal delivery is appropriate.
• Neonatal Prophylaxis:
  • Low-risk infant: Zidovudine (ZDV) for 4 weeks.
  • High-risk infant: Multi-drug ART.
• Infant Feeding: Avoid breastfeeding; recommend formula feeding.

⭐ With effective cART and appropriate management, the risk of mother-to-child HIV transmission is reduced from ~25% to <1%.

High‑Yield Points - ⚡ Biggest Takeaways

• Pre-exposure prophylaxis (PrEP) with tenofovir-emtricitabine is highly effective for preventing acquisition in high-risk individuals.
• Post-exposure prophylaxis (PEP), a multi-drug regimen, must be started within 72 hours of exposure.
• Treatment as Prevention (TasP): Antiretroviral therapy (ART) suppresses viral load to undetectable levels, preventing sexual transmission (U=U).
• Screening all pregnant women and providing maternal ART plus infant prophylaxis prevents vertical transmission.
• Harm reduction via condom use and sterile needle programs is critical.