Effectiveness, uptake and delivery of non-occupational HIV post-exposure prophylaxis (PEP)


Key take-home messages
  • HIV post-exposure prophylaxis (PEP) is a safe and effective strategy aimed at preventing infection in those with a recent HIV exposure. PEP is for emergency situations and not a substitute for regular use of other HIV prevention strategies. PEP is not the right choice for people who may be exposed to HIV frequently, and pre-exposure prophylaxis (PrEP) may be better suited to those with ongoing HIV risk.
  • PEP is typically prescribed as three HIV antiretroviral drugs, started within 72 hours after exposure, and continued for 28 days. Recommendations and guidelines are in agreement that 72 hours after exposure is the longest possible timeframe for PEP initiation, and that PEP is unlikely to prevent HIV infection if it is started more than 72 hours after a person is exposed to HIV.
  • Although recommendations and guidelines agree that “the sooner PEP is started after a possible HIV exposure, the better”, there is a difference among jurisdictions regarding the exact timing of PEP initiation within these 72 hours. For example, a much shorter timeframe of two hours is considered “ideal” by the New York State Department of Health, and PEP initiation “as soon as possible” after exposure is recommended by the British Columbia Centre for Excellence in HIV/AIDS, the Australasian Society for HIV,  the British HIV Association (BHIVA), and others. According to British HIV Association (BHIVA), PEP should be initiated “preferably” within 24 hours. The European AIDS Clinical Society guidelines suggest that PEP should be started ideally <4 hours after the exposure, and no later than 48/72 hours.
  • While initial patient acceptance of HIV PEP is high, adherence, clinic follow-up, and documented completion rates of PEP vary across studies and population groups. PEP adherence and documented completion appear to be low among people who experienced sexual assault.
  • Having high-risk sexual behaviours and a history of sexually transmitted infections are associated with higher PEP uptake, whereas insufficient knowledge, underestimated risk of exposure to HIV, social stigma, and other factors might hinder PEP uptake among men who have sex with men.
  • Seroconversions among high-risk men who have sex with men who had used PEP in the past suggest that other prevention strategies such as PrEP are needed for this population group.
  • PEP delivery strategies implemented in different settings include: post-exposure prophylaxis-in-pocket—PIP (providing people with infrequent high-risk HIV exposures a 28-day prescription for PEP before an exposure occurs), and advance provision of self-start home packs (“HOME PEPSE”, a 5-day starter pack for men who have sex with men to self- initiate PEP to reduce time to first dose following HIV exposure).
  • Providing PEP starter packs (a 3- to 7-day supply of PEP medications at initial presentation to health care before the full 28-day prescription is provided at a subsequent visit) are used in some jurisdictions and settings, but there is evidence suggesting that these starter packs may not improve adherence to PEP and may result in lower adherence and completion rates.
  • The literature suggests a need for health care providers’ support and capacity building to ensure effective PEP assessment and its optimal use.


The Ontario HIV Treatment Network: Rapid Response Service




  • Epidemiology and Determinants of Health
    • Determinants of Health
  • Determinants of Health
    • Health services
  • Population(s)
    • General HIV- population
  • Prevention, Engagement and Care Cascade
    • Prevention
  • Prevention
    • Biomedical interventions
  • Health Systems
    • Delivery arrangements


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